Multiple blogs ago, we discussed the wisdom of preflighting flaps by running them full down on the walk-around. That subject was about a fatal accident in Detroit involving a heavily loaded C-172. Witnesses saw the aircraft takeoff with full flaps, struggle into the air, and crash—four fatalities. If inclined, you can reread the commentary and opinions, which slightly favored following the manufacturer’s checklist. That means if it’s on the list do it—if not, it’s optional.
There was another flap accident (also fatal) last week involving a C-150 that resulted in the loss of a 20-year old student and his 33-year old CFI. My usual disclaimer about preliminary speculation applies, and you may chime in with similar protection. The sea-level runway had a density altitude of perhaps 2,000 feet in summer temperatures. The runway was 3,700 feet with an estimated 500 yards of overrun before encountering more than 50-foot trees. Witnesses saw the 150 take off with full flaps and barely get airborne in ground effect.
After getting airborne, the flaps were retracted; the aircraft climbed slightly, appeared to be out of ground effect, and wobbled before nosing straight in. The CFI had mentioned to one of the witnesses that he had been up much of the night with a sick child, raising the issue of potential fatigue.
What happened here, in my view, was not a long chain of judgment errors but rather a lapse. A lapse is where one omits or commits just one action that triggers the event. Other examples would be an altitude bust or forgetting to raise or lower the gear. There are actions to guard against them, but sometimes—despite long rants here and elsewhere—the path to catastrophe can be brutally short and swift.
A couple of quick thoughts for your consideration since we’ve hashed this out before:
1) Leave the flaps up on preflight. You’ll find out soon enough if they work—either on takeoff or landing—before getting to a critical situation. This is my personal favorite—the preflight flap craze appears to have come into vogue in the 1990s, perhaps after somebody got sued.
2) If you insist on checking flaps during the preflight, set them no lower than to the max lift setting. In most Cessnas, for example, that will be 20 degrees. That way, if they’re forgotten before takeoff it won’t be a disaster.
3) Another technique, if your aircraft system allows, might be to lower the flaps, turn off the master switch, and then position the flap switch to up so they will automatically retract when the master is turned on for engine start.
4) Fatigue, illness, or medication increases our ability to lapse. That leads to the judgment issue preceding the lapse of whether today’s flight is a good idea. You can see where that is going and something we’ll discuss in the future.
My office overlooks the ramp, and I’ve seen more than a few aircraft taxi out with flaps still down: One lapse away from a major problem? So far this year, there have been six fatalities due to a procedure that was designed to prevent them. The law of unintended consequences applies here. I know pilots shouldn’t be making basic mistakes, but good luck with that line of thinking. Better to avoid putting yourself into a bad situation than to always avoid the small but deadly lapse. That’s called risk management.