Jun 18, 2007

A Day in the Life (24) No Cause For Alarm!

A description of a typical day's flight from Montreal to Vancouver and back - 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 - Cruise

Time: CYVR Arrival minus 4H00M

“Leaving flight level two six zero for flight level three five zero, Climb, Open Climb.”

I’ve organized the clearance with Toronto ATC who had to talk to Winnipeg ATC and finally we’re on the way back up. Before doing all this I had a long chat with Connie about the cabin service. Breakfast is finished and they’ve re-secured all the carts and galley equipment. I made an announcement to the passengers to let them know we’ll be climbing soon to try find a smoother ride.

When giving passengers technical announcements, it’s a bit of a head-scratch finding the right words. I don’t want to overload them with details they won’t grasp anyway. And I don’t want to give them a long song-and-dance that could be misunderstood. And I don’t want to frighten them. Yet, with turbulence I seriously want them to stay seated with their belts tightened up.

I recall an old Carol Burnett show about pilots making announcements. I won’t even mention this to FO Paula because she’ll just look puzzled again and ask “Who’s Carol Burnett?” and I don’t have Youtube on the flight deck. At least not yet. “Ladies and Gentlemen, there is no cause for alarm…” I’ve always wanted to make that announcement.*

But today I just tell them about the likelihood of more turbulence as we climb towards hopefully smooth air. And while I’m at it I give them a standard announcement about route and arrival times and Vancouver weather. And thank them for their business. Might as well try to win them over before they are terrified and puking.

The chop at FL260 has been intermittent, and initially the climb looks like a good idea. The air at 270 is almost smooth. And then it gets gradually worse and worse. At FL310 it’s really uncomfortable. The airframe is taking some solid hits and rocking and pitching away from the target attitude. When it's this rough up front I know it's a lot worse in the back. If this lasts long, the sick sacls will be in big demand back there.

My seatbelt is digging into my lap from time-to-time and the airspeed tape jumps plus and minus ten knots. The airspeed trend arrow reveals where the trolls figure our speed will be ten seconds from now based upon current conditions. They must be burning out their abaci because one second it shoots upward, then the next it just as aggressively stretches downward.

We’re the first to climb through these altitudes in this particular region and I know everyone on the frequency is wondering how it’s going. I call ATC to tell him we are getting some “good moderate turbulence through flight level three one zero.” We actually have a table*** defining the words we use to describe turbulence. When someone says “good moderate turbulence,” that’s not good. It means they’re being careful to avoid the word severe, and yet want to emphasis that it’s a really rough ride.

Finally at 330, there’s some sign of relief. FO Paula has us climbing at the turbulence penetration speed which also gives us the maximum rate of climb. But it's not much as the engines produce less and less thrust in the thinner air.

At flight level three-five-oh, the ride isn't great - but tolerable. The “jaws of death**” on our airspeed indicators and the performance numbers in Macdoo tell us we could manage to get up to three-seven-oh.

FO Paula is thinking the same way. “Do you want to ask if three-seven-oh is available?”

I do. I ask.

“GooseAir, cleared to climb to flight level three seven zero.”

Our rate of climb barely averages four hundred feet per minute now. But the higher we climb, the smoother it gets. I keep checking the outside air temperature. If it is much warmer than normal up here that could cause us a problem. Warmer air also means less engine thrust.

“Mach, ALT Star,” FO Paula reads out as the autopilot begins to capture the new cruise level. It takes a long time to gain the last two hundred feet because we seem to be losing headwind as we climb. The engines have barely enough excess power to keep us climbing, let alone regain each knot of headwind that shears away.

Finally we lock on to the altitude and I check the wind indication and groundspeed. It’s good. We’ve managed to get above the turbulence along with much of the prevailing westerly wind. In a minute when things settle down I’ll recheck our fuel picture, and make a pirep to flight dispatch, but for now I’m happy just to key the mike and report; “GooseAir one eleven is level at three-seven-oh. Mainly smooth. Just an occasional ripple."

I turn to FO Paula. “You do good work. Remind me to give you a raise.”

“I wish,” She responds.

I reach up and flip off the seatbelt sign.

Time: CYVR Arrival minus 3H40M

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** Jaws of death: The airspeed tape shows our maximum speed at this altitude with a red bar, and our minimum safe flying speed with an amber bar that becomes more serious shades of red and yellow further down the tape. Sometimes when we’re cruising at our maximum permitted altitude for our weight, there is as little as 8 or 10 knots between maximum and minimum. And in turbulence these indicators close in on each other. So, they’ve been knick-named the jaws of death because should they ever come together it Bites! big time. (see previous references to coffin corner and jet upset.)

*** The Table of Turbulence Definitions and Reports:

INTENSITY Light:

AIRCRAFT REACTION
Turbulence that momentarily causes slight erratic changes in altitude and/or attitude (pitch, roll, yaw). Report as Light Turbulence.* OR Turbulence that causes slight, rapid and somewhat rhythmic bumpiness without appreciable changes in altitude or attitude. Report as Light Chop.
REACTION IN AIRCRAFT
Occupants may feel a slight strain against seat belts or shoulder straps. Unsecured objects may be displaced slightly. Food service many be conducted and little or no difficulty is encountered when walking.

INTENSITY Moderate:

AIRCRAFT REACTION
Moderate Turbulence is similar to Light Turbulence but of greater intensity. Changes in altitude and/or attitude occur but the aircraft remains in positive control at all times. It usually causes variations in indicated airspeed. Report as Moderate Turbulence.* OR Turbulence that is similar to Light Chop but of greater intensity. It causes rapid bumps or jolts without appreciable changes in aircraft altitude or attitude. Report as Moderate Chop.

REACTION IN AIRCRAFT
Occupants feel definite strains against seat belts or shoulder straps. Unsecured objects are dislodged. Food service and walking are difficult.

INTENSITY Severe

AIRCRAFT REACTION
Turbulence that causes large, abrupt changes in altitude and/or attitude. It usually causes large variations in indicated airspeed. Aircraft may be momentarily out of control. Report as Severe Turbulence.*

REACTION IN AIRCRAFT
Occupants are forced violently against seat belts or shoulder straps. Unsecured objects are tossed about. Food service and walking are impossible.

INTENSITY Extreme

AIRCRAFT REACTION
Turbulence in which the aircraft is violently tossed about and is practically impossible to control. It may cause structural damage. Report as Extreme Turbulence.*

REACTION IN AIRCRAFT
The official table doesn't actually have anything to say about this. At any rate it won't be 'good' and will probably involve a lot of fear and vomiting. And may even generate a complaint letter to the airline president assuming The Wings Stay On!

*High level turbulence (normally above 15,000 feet MSL) not associated with cumuliform cloudiness, including thunderstorms, should be reported as CAT (Clear Air Turbulence) preceded by the appropriate intensity, or light or moderate chop.

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*I recall this being performed by Harvey Korman, Tim Conway and Carol Burnett, but I can’t find that. Here’s a Monty Python version:


Related Carol Burnett Show skit:

1 comment:

moe said...

Ah those clips were great!