Apr 21, 2007

A Day in the Life (16) - Take Off, Eh!

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 - CYUL - Take Off

Elapsed Time: Take-Off plus zero

FO Paula smoothly presses the thrust levers forward to set the donuts at thirty percent. When both engines are responding equally she continues pushing smoothly through the climb power detent, clicks again through the slot marked FLEX, to the TO/GA detent (TakeOff/GoAround).

One of the first things pilots have to get used to on jet aircraft is the silence. Where other airplanes during the take-off produce walls of noise and syncopated beats from propellors and exhausts, the jetliner simply accelerates. There may be an increase rush from the overhead airconditioning vents. There may even be a detectable rumble from wing-mounted engines - but if your new jetliner has tail-mounted engines it’s even more likely the takeoff will seem eerily silent.

So we depend upon the needles and guages more than ever to set the power correctly and there may be some seconds of fine-tuning levers to get needles lined up ‘just so’.

But thankfully Airbus has automated away this fiddly process. Once the levers hit the TO/GA detent, the EFCUs (electronic fuel control units) set the engine to Take Off / Go Around . It’s so typically Airbus that they call this setting TOGA which is the legal definition used in certification I suppose. The engine design specs allow us to use this much power for up to ten minutes.

I notice our navigation display shifts slightly now to put us at the beginning of the runway, and then I quickly scan the engine gauges for nominal values as FO Paula releases the levers to me. At GooseAir the captain holds the engine levers until V1 - the decision speed. Up to that moment if something ‘bad’ happens, he only has to snap the power levers to idle and immediately trigger the rejected takeoff.

Today all goes well. We’re heavy so V1 is 160 kts. and it takes nearly a minute of acceleration to get there. Knowing what I do about high speed rejected takeoffs, my tension level rises with the airspeed.

“One hundred,” I call as the ASI reaches one hundred knots. “Roger,” FO Paula responds. This cross-checks our airspeed readings and confirms that the pilot flying is not comatose. It also signals that forward pressure is no longer required on the control stick to aid directional control and finally it reminds us that we are entering the high speed regime in the event of an RTO. Up until now I would have rejected the takeoff for most any irregularity. It’s easier to deal with problems on the ground. But from here on I’ll only reject for significant threats to our safety.

I quickly glance at the engine parameters and then outside and repeat this several times during the roll, hoping the engine temperatures will remain normal. Engine two EGT is slightly higher than number one, but well below the red line. Good.

The airplane lumbers along the runway reminding me we are near our maximum take-off weight. As the speed builds I begin to hear a hum from the nose-wheel below and slightly behind. I've always suspected that someone with a good ear could call Vr (the rotation speed) by that sound alone. "There's "B sharp, wait for it... yes, there's High C! Rotate." Imagining the centrifugal forces at work reminds me that tire failures cause more takeoff incidents than engine failures. Yet in the flight simulator we practice a variety of engine problem scenarios and rarely delve into tire problems.

“Vee one.” The magenta marker on the airspeed "tape" slips past the reference line. I ease my hand off the thrust levers. Then call, “Rotate,” as Vr slides by as well. FO Paula is already easing back on the control stick. The nose of the Airbus lifts. The target rotation rate is 2 to 3 degrees of pitch per second. Any slower would tend to prolong the ground roll. Any faster might also increase the ground run and would certainly increase the chances for a tail strike. The airplane is protected by a skid, but if it hits the runway hard enough to shear the indicator pin a special inspection is required for possible hull damage.

FO Paula is as smooth as usual and the windshield rapidly fills with blue, or at least hazy white this morning. There’s a short hesitation, followed by a solid thump as the main gear legs hit one last rough spot in the runway and then bottom out in their cylinders. We have broken free of the ground. The nose continues to lift until it stabilizes just below fifteen degrees nose-up attitude.

The VSI needle flutters then surges towards positive territory along with the altimeter tape moving skyward.

“Positive rate.”

“Gear Up,” She commands.

I reach across the center panel to flip the wheel-shaped switch up. Gear lights begin flashing through their sequence of red and amber and then wink out as the nose-wheel thuds home beneath us and spins down, buzzing slightly against the brake-pad. The main gear brakes pulse automatically during the retraction to stop the main wheels from spinning in their wells.

The nose gear doors thump closed and the flight deck returns to calm once again. The altimeter says we’re climbing, but not rapidly. The VSI settles in around one thousand feet per minute. But we are airborne and on the way. Up.

Elapsed Time: Take-Off plus...

2 comments:

Chris said...

If 1000' per minute isn't rapid what is?

Aluwings said...

How about 5,000 fpm! Or more typically, 2,000 fpm+ ...

Your comment developed into my next posting - thanks.