Sunday, October 19, 2008

Rudder and Stick

We all know that the "good old days" when you flew instruments using needle, ball, airspeed, and altitude are long gone. The "good old days" of flying by the seat of your pants and feeling the slipstream on your face are even longer gone. Oh, there may be a few wackos, myself included, who have spent some time flying sideways in a tube-and-fabric airplane in order to stay over the road they're following in a strong crosswind, feeling the wind through the open window (or, in may case, the bad door seal), but the trend in aviation these days is to deploy a simulator-and-classroom trained crew in a highly automated airplane. Some countries have already implemented the MPL, or Multi-Crew Pilot License, whose privileges do not include solo flight. MPL holders may fly as part of a crew, but may not be PIC in a single pilot airplane.

So now we come to the saga of 9M-MRG, a Boeing 777-200 operated by Malaysia Airlines. In 2005, it left Perth, Australia, headed for Kuala Lumpur. Climbing through FL360, things went very wrong. You can find the Australian Transportation Safety Board report here.

Modern aircraft have pitot-static systems, just like my old Taylorcraft, but blend the data with data from accelerometers, GPS, and the like. In many cases, the magnetic compass display is actually computed from the true heading, using a mathematical model of the Earth's magnetic field. So an in instrument is no longer just an instrument; it is a summary of a lot of data, much of it hidden from the crew. Furthermore, a flight control is no longer just a flight control. Autothrottles mean that a crew asks for, say 65% power, and the computers do the rest.

That day, an accelerometer (#6, to be exact) failed. Accelerometer #5 had previously failed, and a software error combined with the two failures led to chaos. The crew got simultaneous overspeed and underspeed warnings, and the airplane pitched up nearly 20 degrees. Airspeed decayed rapidly, but the autothrottles kicked in. The crew disconnected the autopilots and autothrottles and hand-flew back to Perth, where there was a 25 knot gusty crosswind. The bureaucratic jargon for "sweet" is "uneventful landing."

The highest that I have hand-flown is FL 310, where the air density is about 35% of its density at sea level. Even at that relatively low altitude the air is noticeably thin, and hand-flying takes a deft touch. Perversely, with so little air hitting the control surfaces, it is very easy to overcontrol; I have watched a lot of guys try to handfly in the high 20s and spend the afternoon chasing their tail. So I admire the crew that got this airplane on the ground safely.

The reports say nothing about the experience of the crew, but I would like to think that at least one of them had spent a few hours on a sunny morning chasing his or her shadow in a Taylorcraft, or squeaking the maximum performance out of a glider, or shooting touch-and-goes in a Champ, or even flying a Cessna 152 for a $100 hamburger. Because whether you are at 1000 feet and 60 knots, or 38,000 feet and 360 knots, when all else fails you can stick the nose at the right place relative to the horizon and spend the rest of the day enjoying the scenery rather than glued to the gauges.

I love instrument flying, the mental visualization of my position, the getting ready at the right time and no sooner, the precise descent, and the perfectly timed turn to intersect a DME arc. And I love visual flying, trying to make the perfect pull on a chandelle or crabbing along the ridge in a glider. I would like to think that when I am watching the world go by in seat 26A someone up front feels like I do.

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