These two websites reveal some of the extremes of aviation - from small and maneuverable to huge and technologically impressive.
A media reporter having an exhillerating ride in the back seat of an F-18
A 360 degree scan of the A380 flight deck.
As with other demanding professions like law and medicine, piloting involves specialization. You can't take a "driver" from one of these environments and just toss him or her into another without extensive re-training. And once the pilot is deemed competent flying the new machine the long slow process of gaining experience in the new speciality is just beginning.
Jan 30, 2008
These two websites reveal some of the extremes of aviation - from small and maneuverable to huge and technologically impressive.
Jan 28, 2008
The investigation into British Airway's B-777 landing-short accident is apparently now concentrating on fuel. This article indicates fuel contamination is high on the list of suspects. Also:
" ... Sources also tell The DAILY that upper air temperatures over Russia and northern Europe were extremely cold on the day of the accident. Information from other crews coming from Asia on Jan. 17 encountered extremely low temperatures in the -70 to -75 degrees C. range, resulting in fuel temperatures dipping into the -40s. European upper air temperatures also indicate the last 6.5 hours of the inbound China flight would have been flown at an outside air temperature of -60 deg. C. or lower. Although this would have resulted in fuel temperatures on approach in the -35 degrees C range, this would not normally constitute a problem unless, potentially, contaminants were present."
The fact that the fuel temps were close to the minimum allowable range is interesting. Jet A fuel has an "official" freezing point of -43 degrees C., but the minimum allowable temperature of the fuel in the tank on the A320 aircraft (for comparison) is limited to -36C. This has to do with viscosity changes and "slushiness" that can occur causing cavitaition problems for fuel "boost" pumps inside the tanks.
Some aircraft have used strategies to circulate cold fuel (in wing tip tanks) with warmer fuel (for example, in body tanks) to allow for extended flight time in very cold conditions. I don't know if the B-777 does this.
Prior to fuel reaching the engine, it passes through a filter. A significant drop of pressure across the filter is interpreted as ice crystals forming, at which point a fuel heating system will kick in. The Second Officer manually controlled this system on older aircraft such at the B-727. There were cases where engines lost power because the system was inadvertantly left on too long, triggering fuel vaporization in the lines.
I'm sure all these factors and others will be investigated closely to determine if the fuel system operated normally or somehow contributed to the problem.
Jan 27, 2008
Another possible explanation focuses on wake turbulence as the cause of Air Canada 190's upset earlier in the month, according to this article and reported here:
To help you visualilze wing tip vortices and wake turbulence I found these videos on Youtube:
Early research - note how long vortices persist...
Altitude research - note the sudden rolling movement induced on the B737
The size of the vortices increases with the size of the airplane. So it is routine for smaller aircraft to be spaced further behind larger aircraft. If a B-747 was flying ahead and above Air Canada 190 on this route, there is certainly a possibility that the vortices may have been the cause. Unhappily in most weather conditions, there is no way for pilots to see these air currents, nor do we have any instruments to detect them.
Here's a link to more information on vortices at Wikipedia:
Jan 24, 2008
Captain Robert Pearson and First Officer Maurice Quintal, the flight crew who landed the aircraft to safety in Gimli on July 23, 1983 are expected to be on hand for the aircraft's departure.
Jan 20, 2008
In the wake of the British Airways B777 crash at Heathrow last week I'm sure many interested parties will be eagerly awaiting the outcome of the investigation. The only official statement so far that I've seen states that at 600 feet above the runway, the auto-thrust commanded more power from the engines but they both failed to respond. The pilot subsequently moved the thrust levers but there was still no response.
Some of the investigation parameters which I'm sure will be considered - in no particular order:
How much was still on board? How much was boarded at point of departure? Any indications of abnormal consumption? Any possibility of contamination? Was the fuel deicing system operating properly? Any irregularities in fuel management? Any inrregularities in the fuel supply system? ...
Was the autothrust command received at the engine electronic controls (FADEC)? Were there any irregularities in the FADEC and auto-thrust systems? Were there any electronic problems, irregularities, electrical supply problems or history of problems?
Were normal SOPs (Standard Operating Procedures) followed? Was the correct mode selected for the phase of flight? Were there any irregularities in procedures at any time during the configuration of the aircraft for the approach? Did the aircraft descend through icing conditions before the approach and if so was the proper anti-icing procedure applied? Did the pilots change mode selections or cancel the auto-thrust when the engines failed to respond? At what point did the pilots detect the problem?
Do these engines have any history of unspooling at low speeds (that is rotating too slowly due to low airflow through them)? Did they experience aerodynamic stall (unspool) during this approach? Did they ingest any foreign matter, birds, ice, water, etc.? Did they show any sign of responding to the power commands at all (it is typically normal for a jet engine to take up to 8 seconds to accelerate from idle to full power).
This is just a quick list and I'm sure there are other aspects that will be investigated as well. As you can tell, it's not always a simple thing to determine the cause of an accident. Meanwhile, CEOs of airlines operating these engines, as well as Boeing and Rolls-Royce will be watching closely. As will be line pilots flying Trents. Personally, if I was one -- I would probably use manual-thrust approaches for the time being...
Trent 800 Series
The Trent 800 family powers the Boeing 777. It is available on the 777-200, 777-200ER, and 777-300 variants, with thrust ratings spanning 75,000 to 95,000 lbf (334 to 423 kN). No airline operates the engine with greater than 93,400lbf thrust however, as it has yet to be certified to any higher level for commercial operations. The engine is one of the lightest in its class; a Trent-powered Boeing 777 weighs up to 3.6 metric tons less than General Electric and Pratt & Whitney-powered versions.
* Three-shaft high bypass ratio 6.2 - 5.7
* Fan diameter: 110 inches (2.79 metres)
* Eight-stage IP compressor
* Six-stage HP compressor
* Single annular combustor with 24 fuel injectors
* Single-stage HP turbine
* Single-stage IP turbine
* Five-stage LP turbine
Cutaway diagram from Rolls Royce:
Jan 18, 2008
Jan 16, 2008
So, if the A319 which experienced a sudden flight upset earlier this week was not struck by clear air turbulence, what other factors could account for the roll oscillations reported? Here are a couple that come to mind:
Modern Jet Transport autopilots provide inputs on all three aircraft axes. But normal roll or steering inputs would never command the steep bank angles reported. If there was an automation-related failure, it would have to be something very unusual.
One key part of the autoflight system that may be associated with sudden roll inputs is called a yaw damper. How does yaw interact with roll? By design all modern aircraft will immediately begin to roll when they experience any significant yaw. And this effect is magnified by swept wing configurations. In fact, on most aircraft and certainly on swept wing aircraft, pilots will generally notice and react to the rolling caused by unexpected yaw much sooner than we'll notice the yaw itself. In flight simulators, where we practice engine failures during takeoff, we have to condition ourselves to apply necessary rudder inputs to stop the yaw rather than becoming distracted by the noticeable roll that results as well.
A failure in the yaw damper system could cause large and sudden roll movements, but again, this would require a pretty rare and drastic failure mode. Notably, the Boeing 737 has had some serious accidents and incidents attributed to the rudder suddenly moving "hard over:"
Another potential cause could be an inadvertant overspeed of the aircraft causing shock waves to form on the wings. Any uneveness between the left and right wing could cause some sudden yawing-rolling motions. But again, this is unlikely due to the over-speed protection features built into the Airbus flight envelope protection system.
One other source of sudden, inappropriate control inputs could be the pilots themselves, either a foot slipping and hitting the rudder pedal (see the notes above about yaw and roll), or accidentally leaning against the Airbus joystick - which apparently has happened before according to this report from an aviation forum:
When my company first got their A320's we had similar incident. The cause was put down to the F/O sitting cross legged and his Knee pressing on to the side stick. If I remember correctly they thought either the pressure gradually increased until the autopilot let go or that he moved and knocked the side stick hard over. Neither pilot could remember this happening but the FDR showed the side stick movement.
Again if I remember rightly the a/c went 60 deg one way then 60 the other as the other pilot grabbed his side stick to correct. Then a bit of dual stick input (it sums the inputs) until things settled down. Luckily no one was hurt.
So, you can see that even if clear air turbulence is ruled out, there will still be a lot of other factors to study before the real cause will be known. The investigation process may take a while yet. In the meantime, Airbus Inc. and airlines who operate large fleets of A319s will be watching closely. As will stockholders and of course pilot associations.
Time will tell.
For detailed discussions of aircraft control and flight dynamics :
Comments found online regarding the recent Air Canada A319 "upset" incident now seem to reduce the likelihood that turbulence was the culprit.
For example, this comment by a jet transport pilot who was a passenger on AC190 (emphasis added):
I was on AC 190 yesterday. ... we were in smooth air in cruise when the plane rolled abruptly to the left followed by a roll reversal to the right. There were then about 3 more roll reversal that were getting small in intensity. It seemed to me that after the first roll upset the crew was getting the Plane back under control. ... After the crew had the Plane back under control the Captain made a PA and said that they had had a computer malfunction and that the problem had been isolated and that they were manually flying the Plane. The rest of the flight was smooth with a nice landing in YYC. I just wanted to say thank you to the crew for getting us on the ground safely.
Then, these comments from a Transport Safety Board official as quoted by CBC (again, emphasis mine):
"The aircraft rolled to the right to about 35 degrees of bank and rolled to the left about 50 degrees of bank and effectively the auto pilot was disconnected," said Nick Stoss of the Transportation Safety Board.
The upset was apparently a sudden rolling movement of the aircraft which is not what I would expect from CAT/Turbulence encounters. Further laying the CAT hypothesis to rest are the comments about smooth air before and after the incident, and a previous report that said that the pilots did not log an official report of turbulence with ATC.
Flight control problems of one sort and another now take on greater importance in my mind. A sudden roll to one side (interestingly the two reports differ about which direction happened first.) followed by an even further roll in the opposite direction followed by diminishing rolls suggests that one or both pilots over-reacted to the sudden movement, causing momentary oscillations, before restabilizing the plane to level flight.
Reports of the aircraft "plunging" are also easily explained. Any time an aircraft banks to extreme angles it becomes more difficult to maintain altitude. This is exaggerated the higher we climb into the thinning atmosphere. So along with any altitude loss caused by those huge rolling movements, I'm sure the pilot also initiated an immediate descent.
What sort of malfunctions might be suspected? More thoughts on that coming up...
Jan 15, 2008
Autopilots have limited authority and a specific flight regime they are capable of handling. When the pilot does not properly account for this, it's a setup for disaster.
Case in point - China Airlines flight 006, Feb. 19, 1985:
When an engine fails in cruise flight, the Captain's slow and often inappropriate reactions lead to the autopilot severely mis-trimming the aircraft. When the Captain finally disengages it, all hell breaks loose:
When I first read this incident report, I thought that the Captain was somehow deficient. For example his initial decision after the incident to continue to destination was ludicrous. In retrospect, it seems he may have been suffering his own kind of limitations that all carbon-based pilots must contend with:
(from the report summary):
...this incident brought to international attention the problem of jet lag as a contributing factor to pilot errors. The captain was considered to be highly experienced and had flown six international flights in the previous two weeks. Though he testified that he did not believe he was tired, NTSB investigators suggest that his inability to sleep during his rest period and the fact that the incident took place at 2 a.m. Taipei time contributed to his inability to focus on and process important details about the aircraft's behavior that could have averted the incident.
There's something special about the feeling of lifting off, supported only by the air. The vision of a society where everyone has access to the skies by means of simple and inexpensive aircraft has been around for a long time.
Thanks to this inventor, maybe we won't have to wait for The Jetson's version of the future - but don't hold your breath either. This unit looks pretty unstable! An old aviation adage seems to apply here: "Don't fly any higher than your're prepared to fall."
It's not unusual to have to deal with last minute changes when departing Chicago's O'Hare airport, especially during difficult weather. You never know if you'll end up sitting in line for half-an-hour or more, or blasting right out. These are my notes from one such event:
(Note that the entire time frame for this departure is less than 15 minutes during which we are going through several radio communications with ramp control, ground control, company ops, tower, departure control, did I forget anyone? And our radio is continually busy with controllers and other pilots. Through all this it is considered a cardinal "sin" to miss any calls the ORD controller has for our particular aircraft, so we must never stop listening out while dealing with our flight deck issues... all part of the fun.)
Log Entry - A319 Capt - KORD - At the Gate - Departing - lines of heavy thunderstorms in the area...
•Thunderstorms and rainshowers affecting arrival/departures. Nothing drastic
happening on the airport itself besides intermittant light rain and wet runways due
to a heavier shower in the past hour.
•ATIS gives a northeast wind approx 15 kts, good ceiling and vis. Runways 4L, 9L
and 32L from T10, for departure.
•We program 4L in the primary navigation page with 9L in secondary. We pull up the chart for 32L@T10 and check the numbers for this runway also.
•Flight planned to Montreal (YUL) at flight level 370 with YMX alternate. Alternate requirement is in ‘the gray zone’, but due to amended forecasts, it’s nice to have the 400 extra. Plan also includes 800 ATC/WX fuel for ground delays and enroute diversions.
•I decide to start 2 engines on pushback due to ramp congestion in the gate area
as well as the need to expeditiosly get ‘over the hump’ at the top of the alleyway
(taxi weight about 59,000 kg.). APU kept running for later engine shutdown/restart once
we get onto the taxiways and assess the length of delays.
•While at top of alleyway waiting for ground control to assign our taxi routing, ‘*PACK 2 OVERHEAT’ ECAM warning comes on. ECAM action -- pack switch OFF until temp returns to normal...
(*note: we have 2 'Packs' which supply compressed air for pressurization and air conditioning).
• (warning - more tech talk:) The presentation is confusing at first because the pack outlet temp is high, but green. I’m expecting an amber temperature indication. I notice later that the small line leading out of the pack is amber and so this must be an Air
Cycle Machine overheat type of ‘trip’ -- ah takes me back to my B727 S/O days.
•We are assigned to runway 4L for departure - with significant delays - all
southbound departures are on ground stop. Turn LEFT along Alpha to Alpha 12
then double back on Bravo to join the lineup for 4L. Go! Go now! I jump us forward into the flow of airplanes along Alpha...
•Meanwhile the pack warning is taking a long time to go away. I wonder if shutting
down the engine will ‘mask’ the problem only to have it reappear just as we restart
the engine when we are at the front of the lineup and no time left to fix things... I
decide that this probably isn’t an issue, but should be prepared anyways for such
•We shutdown engine 2 while taxyying. I hand control of aircraft to FO so I can haul
out the gigantic MEL manual (we should have a crane installed!), and set it on the
floor where he can reach it and ask him to see ‘what if’ the pack
overheat doesn’t go away.
•I make a quick ‘takeoff delay’ type PA for the Passengers and Flight Attendants.
•I take back control of the airplane and the FO checks the MEL messsage list to confirm it is NOT a NOGO item, then checks for any RTG (return to gate) requirement. The max. flight level is 315 with one pack and RTG applies only if more fuel is required.
•We enter FL290 (direction of flight) into the Prog page and confirm that the extra
fuel is adequate if the need arises.
•ORD ATC advises that they will have a re-route for us to send us further northward with a
departure off 32L@T10. We are cleared to turn left at Alpha 9 over to Tango and
hold short of T10. Contact ORD tower at frequency xxxxx for full re-route.
•This means we are suddenly number 1 for departure on 32L as I see no other
aircraft lined up on Tango! I advise that we have a ‘technical issue’ we’re
working on and offer to pull out of the traffic until it’s cleared. The
controller says “no, don’t do that or you’ll be stuck here for much longer -- better to
get the re-route and then coordinate the ‘issue’ with the tower" -- ya gotta love those ORD
•We set aside the MEL for a minute to concentrate on the re-route clearance. We
are given a departure over PETTY - Muskeegan - Peck - YXU - MSS - Cedar arrival
YUL. Happily the FO had this similar reroute last month so he knows how to
‘spell’ Muskeegan (that is it's coded database name: MKG). Otherwise I would have asked the controller for the spelling. One advantage of the FMGC system is that when we know the actual ident codes for the stations, it is much easier to handle last minute re-routes without having to pull out clumsy navigation charts and frantically search for unfamiliar waypoints.
•We reprogram the departure runway for 32 left from the Tango 10 intersection and the new route and recheck the fuel requirements. Extra is still good (I love the ease of fuel checks on the FMGC as well).
•Finally the pack overheat goes out and we reset the pack. It stays normal.
•We start Engine 2; shutdown APU and get going on the Before TakeOff checklist.
•Quick PA to Passengers and Flight Attendants.
•We are number one at the 32L@T10 and as fast as we can get ready the controller
sends us to position and gives us our takeoff clearance with a right turn to 010
heading -- right towards the west end of a rainshower area. The radar returns on
the 40 mile scale are only amber so we accept it and ‘roll’. I hand control over to the FO as it's "his leg."
•The runway is dried out enough that the FO uses FLEX (reduced) takeoff power.
•At 100 knots when the ‘wind arrow’ starts to show up on the ND I notice that we
actually have a slight tailwind. I consider pushing the power up to TOGA (full), but the
319 is accelerating so well and the runway is still plenty long, so I decide not to
‘rock the boat’.
•At 400 feet we make the turn to 010 and contact Departure. We are heading straight
towards the rain now and he immediately provides a PIREP - flight ahead reports a
smooth ride with just moderate rain. Did I say I LOVE those ORD controllers!? We get a very
acceptable ride on climbout with level-offs for a few moments at 5,000 and 13,000.
•I advise Flight Dispatch of our new route, fill out the logbook regarding the pack overheat,
enter the USA security sweep info in the book as well, and of course check the
pack temps a couple of times to ensure that all is well. We climb up to 370 as
• The flight to YUL is routine...
Jan 13, 2008
Disengagement of the autopilot is usually a non-event. We do it all the time when we prefer to "hand fly" at any time. But if the aircraft happens to be badly out of trim when the autopilot lets go, bad things have been known to happen.
Case in point:
An appeal court upheld a lower court`s acquittal of a former Japan Air Lines pilot over an autopilot mishap that left a cabin attendant dead. In July 2004, the district court found the pilot not guilty after concluding that he was not aware that his release of the autopilot would cause the aircraft to pitch up and down violently, resulting in the death a cabin attendant and injuries to 13 passengers and crewmembers. In the appeal trial, prosecutors claimed that the defendant could have predicted that his release of the autopilot could cause the aircraft to pitch up and lead to an accident. The accident occurred on June 8, 1997 on a JAL MD-11 jet with 180 passengers and crewmembers. (Mainichi Daily News)
Jan 11, 2008
Moe's question (see previous post) led me to this National Post article which seems to suspect that an Air Canada A319's experience of sudden and severe turbulence was associated with the jet stream. This is certainly one of the first things the investigators will look at. The interaction of jet streams and the underlying Rocky Mountain ranges make this part of the continent a prime spot for encounters with clear air turbulence (CAT).
I pulled a graphic from a recent weather map and you can see that the jet stream takes a sharp bend as it crosses the mountains. It also suggests that moderate turbulence is to be expected between flight levels 250 to 370 in the same general region that this aircraft had its 'event.' (* Please note: this chart has been issued since the Air Canada incident and I have no idea what the charts pertinant to that flight showed. Air is always flowing and changing and even the latest weather maps are "history" by the time they're published.)
If aviatrix was still posting she'd probably have an excellent explanation all about mountain waves, jet streams and turbulence. I don't. But good ole Wikipedia has lots on all three topics:
As to why the pilot would mention the autopilot in his post event announcement: Excursions in airspeed beyond the normal envelope will cause the autopilot to disconnect producing a loud warning so the pilot knows this has happened. It's a limitation of the automated system to ensure that it isn't actually causing the problem. This illustrates once again, that automation is only designed to do certain things. Then we much-maligned "carbon-based units" are required to step in, figure out what went wrong and set things right. Sudden changes in air speed during jet stream and mountain wave encounters have often triggered such disengagements.
And one last comment - when airlines announcements recommend that you keep your seat belt fastened at all times while seated - they mean it. This is exactly why.
Video Report from Global T.V.
One point in this report I find significant is that apparently the pilot did not issue a turbulence warning to other pilots after this encounter. The possibility of an autopilot computer malfunction is mentioned. But another possibility isn't talked about. There is always a slim chance that one of the pilots accidentally "fell" into the control joystick somehow - perhaps while getting in or out of his/her chair... I've never heard of that happening, but often wondered when it would.
The ultimate cause of this incident and whether the airplane was damaged will be determined by investigators using data from the black box and cockpit voice recorders. And until their work is complete, all our speculations are just that. Speculations.
Jan 7, 2008
In order to get this story progressing again, I've decided to just live with a couple of errors I've committed in the story telling, and "get on with it." But for those of you who may notice such things, I'll share this editorial note/correction until I make the necessary changes:
In the posts regarding descent and STARs etc... some editorial changes would make it more realistic..
The clearance for the approach, with the instructions to "...contact towar at the FAF..." should come later in the descent... around GONIR at 6 or 7 thousand..
The problem with altitude limitations should be referenced to STAVE and the 14,000 foot top of the altitude window and speed reduction.
A description of a typical day's flight from Montreal to Vancouver and return - as a backdrop for a detailed, non-technical description of what an airline pilot does. (check left hand column for series index).
Log Entry 2003 - A320 Capt - Descent
Note: The STARs for YVR have been modified since the flight I’m describing. It used to be almost a “straight in” arrival compared to the updated version which introduces a downwind leg (scroll down the page to find a pdf doc for YVR CANUCK STAR):
Time: CYVR Arrival minus 0H06
I key the mic. It’s time to engage Vancouver Arrival in negotiations. When the controller responds to my call, I offer him the choice:
“GooseAir One Eleven. We may be unable to comply with the restriction at GONIR. Do you prefer us to make the airspeed or the altitude restriction first? Or do you need something else completely?”
A short pause.
“GooseAir One Eleven. Get the speed back for me right now and do the best you can with the altitude. There may be a short delay fitting you into my sequence and I may need to turn you here shortly anyway.”
I acknowledge and a quick glance towards my colleague assures me she got the message.
“Well,” she says, “let’s try this…” She sits up just a little straighter, then hits the red button on her joystick. A short calvary charge bleep, bleep sounds as amber cautionary messages appear on the ECAM displays. “Autopilot disconnected," F/O Paula announces. Since Flight 401 crashed into the everglades many years ago partly due to an unnoticed autopilot mode change communications regarding autoflight status have become much more forceful.
There’s a slight increase in the airframe burbling as our speedbrake panels now deflect fully against the airstream. The autoflight system only commnads up to fifty percent of the speedbrake deployment. I suppose it’s a way of limiting aerodynamic changes to stay within the capabilities of the autopilot. But we carbon-based units are trusted to deal with greater force imbalances.
F/O Paula smoothly pressures the nose over to maintain the required airspeed and the vertical descent indicators nudge downwards.
I’m watching the outside air temperatures closely. The clouds are thinning now and the rime ice on the windshield wiper nuts is almost gone. As we descend through seven thousand feet, we begin to see glimpses of the ground. I twist my body around to look back at the leading edge of the wing. The A320 is one of the few airliners where the flight deck window geometry allows the pilots to view of most of the wings from tip to engine. I see the gleam of clear aluminum.
“The wing looks good and clean. How ‘bout we get rid of the wing anti-ice now?” F/O Paula concurs and I stab the appropriate overhead pushbuttons, watch the annunciators change, and detect a small drop in engine rpms and airconditioning noises. The VSI responds again with a small shift downwards. Minus 2,500 feet per minute...
F/O Paula is getting her groove back…
Time: CYVR Arrival minus 0H05
Jan 6, 2008
Jan 4, 2008
Once I get GooseAir 111 to the ramp in Vancouver, I might have a comment or two about ground marshalling and the folks who prepare our parking spot for arrival, then help guide us in.
I've seem some memorable characters doing the job over the years - but none came close to this guy. Not exactly SOP* in anyones book, but you've got to admire the style:
*SOP: Standard Operating Procedures