Welcome to Gadling’s feature, Plane Answers, where our resident airline pilot, Kent Wien, answers your questions about everything from takeoff to touchdown and beyond. Have a question of your own? Ask away!
After an accident, pilots are either portrayed as heroes or villains. I talked a few weeks ago about Chesley Sullenberger’s heroic status, but we may soon see attempts to classify the Dash 8 pilots of Colgan Air flight 3407 as villains.
Much has been reported about the crew of that ill fated flight. Theories began early, as some questioned whether the de-ice boots had been activated (they had) or if the pilots were aware of the icing (they were).
Reports came out detailing how long both pilots had been working at the airline, the number of hours they each had and some even queried the airline as to the experience each pilot had before joining the company.
I long for another couple of years without having to mention an airline’s flight number in the title to a Plane Answers post, but I felt the need this time to clarify a few inaccuracies.
Any time an accident occurs, neighbors and friends will always ask me for an opinion. Just yesterday, the father of my daughter’s school friend asked me about the Colgan accident. I was surprised he was so familiar with the differences between anti-ice and de-ice devices.
It’s been the top story for the past three nights on the national news, so I suppose I can understand his interest. But I’ve learned that speculating on a cause before the preliminary report from the NTSB can often make the ‘experts’ look foolish when the report is released.
I’m never fully comfortable with commenting on something like this–I’m patient enough to wait for the exhaustive investigation that will be tackled by the NTSB.
But in this case, I’ve flown a similar type of aircraft in the state of Alaska, and I’ve run into significant amounts of ice.
So you’d think I would, like many other pilots, jump at the chance to offer a theory. I’ll admit, I’m inclined to think it was icing on the horizontal stabilizer, and that seems to be the leading culprit. We may learn that an issue with the aircraft is the true cause, or the pilots did something out of the ordinary. But it really is impossible to say until the NTSB team issues a preliminary report.
Is tail ice the culprit?
When ice builds up on the tail, the stability of the airplane is reduced, making it more difficult to control the pitch attitude of the plane. As the pilot lowers the flaps on the approach, the tail struggles to do its job. Some might be surprised to learn that the tail doesn’t actually provide lift, it does the opposite. So if the tail becomes ineffective, the nose of the airplane will pitch over.
In this 20-minute video, NASA demonstrates this issue with the same type of airplane I used to fly, the little brother to the Dash 8, the Twin Otter. The theory is the same for the Dash 8. If you really want to understand what the pilots may have experienced, take a look at this fascinating video.
NASA has successfully detailed the ‘feel’ of an airplane loaded with ice on its tail. As the flaps are lowered, or as the speed increases, a tail with as little as 1/4 inch of leading edge ice struggles to hold the nose up. The NASA pilots inadvertently entered a stalled tail condition and performed a perfect recovery by temporarily bringing the throttles to idle and raising the flaps. They managed to lose only 300 feet. But of course the NASA pilots knew what to expect and they knew they were right on the edge of a tail stall.
I’ve experienced light to moderate icing conditions in the Twin Otter, but I don’t remember it being significant enough to affect the pitch stability of the airplane. Perhaps that was because the aircraft was restricted to no more than 10 degrees of flaps after encountering icing conditions, a restriction that might find its way to the Dash 8.
Aviation experts are quick to point out the experience disparity between major airline pilots and those at a regional carrier. But these pilots weren’t exactly inexperienced. Furthermore, It’s unlikely a jet airliner pilot would face the same icing problems as the Colgan pilots that night.
Tail icing is such a non-issue in a jet that many airliners don’t even have anti-icing or de-icing capabilities on the tail. That includes all the popular Boeings, the 737. 757, 767, and 777.
Time for the blame game
Should the Colgan pilots have turned off the autopilot? Maybe so, but that also conflicts with our training that says we may want to use the autopilot to reduce our workload during low visibility approaches.
I have no doubt that a number of pilots that day accomplished that same approach in similar conditions with the autopilot on. It’s unfortunate that it takes a loss of lives to fine tune some of our procedures.
But you can be sure that we’ll see new training scenarios for flying turboprop aircraft in icing conditions, or even new restrictions. Pilots will become so familiar with these procedures and regulations that they may look back years from now and monday morning quarterback the decisions made by the Colgan pilots.
That’s how aviation continues to improve. If it turns out to be a mechanical problem with the airplane, or a training or procedural issue, the Colgan pilots will neither be heroes or villains, but simply victims just like everyone else on board.
But if they’re found to be at fault, as new reports are surfacing, then the villain label will most certainly be applied even before the investigation is complete.
Do you have a question about something related to the pointy end of an airplane? Ask Kent and maybe he’ll use it for next Monday’s Plane Answers. Check out his other blog, Cockpit Chronicles and travel along with him at work.