Nov 20, 2007

A Day in the Life (29) Go!…

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

Time: CYVR Arrival minus 0H15

Step by step Vancouver Center doles out lower altitudes as we progress along the published arrival route. Though I’ve programmed the crossing restrictions and FO Paula checked them before we left cruising altitude, we both have our charts handy to ensure an error free let-down. The mountains below, hidden in the grey and mists, remind us that the cost of a mistake in this region would be sudden and final.

The air is an ocean constantly ebbing and flowing. So every descent is an adventure. Before vertical navigation computers were part of the magic we used the fully portable, self-healing, quickly re programmable carbon-based units conveniently located between our ears to keep a running tab on the descent profile. Even the best laid plans often prove inadequate to the changing conditions.

Now we have magic doodads that supposedly watch all the parameters for us and will never let anything bad happen to us. Right. Any pilot gullible enough to believe that ends up in serious trouble sooner or later.

Today is no exception. The winds down low are not unfolding as programmed and we’re descending below the ideal path. But Paula’s mark seven carbon-based computer, a much newer and fully upgraded model compared to my ancient processor, has already anticipated this and she applies the needed correction by selecting the engine anti-ice system ON, just as we enter the top of the cloud deck.

The air conditioning system surges slightly as somewhere in the bowels of the ship bleed air valves open and computer sensors adjust the engine power to keep the necessary heat pouring into the engine cowls, rotors and stators.

The net result is a little more thrust that begins to push us back onto the planned slope. Which is fine for a while but after a few minutes we begin floating above the envelope as the airplane now glides further for each increment of descent.

I call Vancouver ATC for the next altitude step down, only to be given a handoff to the next frequency. As quickly as I can I flip the radio frequency and repeat my request. There’s a pregnant pause and it looks like Paula might have to interrupt the descent. But just as she begins to bleed off a few knots of speed for less descent rate, our controller delivers the needed clearance.

“Goose Air one eleven, descend to three thousand. Cleared for the ILS two-six-right approach via the Canuck STAR. Call the tower at the FAF.”

This is code language indicating I can now link the final leg of our STAR descent path into the runway approach scheme. The green lines on our Nav screen jumps around for a second as the mystic beasts rapidly reshuffle their abaci. When they’re finished, the magenta donut on the altimeter tape takes a jump towards the bottom of the instrument. With a mile or two less horizontal distance to cover, our descent profile just got a little more above the ideal.

FO Paula is already on it as she reaches across the pedestal and deploys full spoilers.

“In Range Check,” she calls…

Time: CYVR Arrival minus 0H10

2 comments:

Anonymous said...

"But Paula’s mark seven carbon-based computer, a much newer and fully upgraded model compared to my ancient processor"

I love this reference in your post. I have been known to call a headache "problems with the sensitive electronics" in my sleep.

Please do not make us wait too loooong for the approach and landing. I am getting an itch all over wanting to know how you are getting on the ground in Vancouver, and also back to Montreal.

Mario

Anonymous said...

Man,

When are you going to land this airplane?
Enjoy your posts, keep them coming.