Tuesday, February 28, 2006

Handflying the PMDG B738

I purchased FSPassengers some time ago, and it has brought me great joy. Last night I replicated flight SA302 from FACT to FAJS. My settings for FSPassengers allow a 1% chance of something failing in a flight. And last night, for the first time, something did.

After departing RWY01, I switched on VNAV, LNAV and the autopilot, and headed towards WY. All instruments were normal, and I relaxed in the last minutes of darkness before dawn. This was also my first fully laden flight in the B738. 125 passengers, full cargo, and maximum allowable fuel. After all, I had to make money off the flight, and she climbed like a dog.

The autopilot switched off by itself, and my efforts to re-engage it were unsuccessful. A look to the overhead panel resulted in a chill down my spine. It was a mess. The main generators would not activate again, battery was switched off, and I had a fluctuating DC voltage. Switched on the APU, APU generators engaged, and I was able to restore some sense of normal on the overhead panel.

I had no trim, but was able to maintain climb through throttle usage and moderate control yoke pressure. I comtemplated landing at FABL, but since the aircraft was fully flyable, and she was still heavily laden, I decided to push on to FAJS.

RWY03L was active at FAJS, IMC, but I was very glad for the straight in approach. And this is where the trouble started. We were at 240 KIAS 50nm inbound, FL080 came soon, and glideslope intercept was a breeze. Gear down, full flaps eventually, and a near-perfect approach. With a thousand feet to go, I reached full back pressure on the yoke, and I realised that I was in trouble. Not only me, but the crew, and the passengers. When I told my wife about the electrical system failure, she said I should just start over. But how could I? It was about proving whether I had what it takes.

The ground was coming up pretty fast, and my brain just froze. I knew it was over, but I was going to fly her into the ground for as long as I could. Suddenly it dawned on me, the throttles! Full throttle, watching my rate of descent decrease agonisingly slowly. Missed the beacon, missed the ground, the runway threshold came and went, and we set down, bursting tires in the process. But we made it.

For some obscure process, the passengers were happy with the flight. If only they knew. Me, I could have done better. I have no problem with handflying a big jet, but it was a risk I should not have taken. I should have returned to Cape Town after dumping fuel over the Atlantic. But then again, I did deliver my passengers safely, albeit only just.

I am reminded of a plane crash in 2005, northern hemisphere (details withheld to protect companies and individuals), where a businessman had an important meeting in a large city. The procedure called for de-icing the plane before startup, and this took longer than normal due to heavy snow. Not wanting to be late, he apparently phoned the airline company, who in turn ordered the pilot to take off immediately. No one survived the crash, and no one turned up for the important meeting.

The pilot in command maintains ultimate responsibility, and should always have the final say. And even though it is quite a burden to bear, you can not let the thought linger in your mind. For then you may never leave the ground.

To the real-world commercial pilots repeating drills like the above (and much worse) on a regular basis, I salute you.

SA302 - Springbok 302, daily flight departing Cape Town at 06h00.
FACT - Cape Town International
FAJS - Johannesburg International (Jan Smuts)
RWY01 - Runway 01, approximately 010 degrees magnetic.
VNAV - Vertical navigation
LNAV - Lateral navigation
WY - Wolseley Non Directional Beacon
B738- Boeing 737-800
DC - Direct Current
APU - Auxilary Power Unit
FABL - Bloemfontein
IMC - Instrument Meteorogical Conditions (flight by visual reference not possible, pilot has to fly by instruments alone)
240 KIAS - 240 Knots Indicated Airspeed.
50nm inbound - 50 nautical miles inbound to the JSV VOR (Very high frequency Onmidirectional Range beacon)
FL080 - Flight level 080, roughly 8000 feet above sea level, but altimeter setting is for standard pressure.
glideslope - navigational aid assisting a pilot to descend in a controlled fashion to the intended runway for landing.

No comments: