Mishap on the ground

When you think about aviation accidents, most people would immediately think of fires or explosions in mid-air, or collisions with other aircraft, or crashing into the ground or obstructions on the ground.
My friend Chris, who is also learning to fly Tiger Moths, has generously allowed me to retell the story of an incident that befell him a couple of weeks ago. It just goes to show that sometimes it's the simple things which go wrong.
It was quite a windy day, and I expect that contributed to decision making that seems a little foolhardy in hindsight. People get too keen to get airborne if they've spent all day cooped up at the Group, and then as soon as the weather looks at all good, they rush to get out while it lasts. Chris is a little further along the course than me, so it's possible that his instructor was also keen to get him some experience of landing in (relatively) strong cross-winds. Little did he know the kind of experience they would end up having!
Things started going bad as soon as they radioed for permission to taxi. The instructor was to make the radio calls, so he called the tower, and got no response. Again he tried, with the same silent answer. Fearing they'd have to cancel and inspect the radios, they got Chris to make the call on the rear radio. This time they got an answer right away, with their permission to taxi.
Everything was normal until they got to the end of the runway. Again, the instructor was unable to make the radio call, and Chris had to do it. As I've said before, the tower gives you the current wind speed and direction with your departure clearance, so you can be sure it's safe to go. On this occasion, the wind was 15 knots with gusts of 26 knots. That's way outside the limits, even for the instructor, never mind a student. Chris read back the clearance before even thinking about it, then noticed that the controller had sounded quite surprised they were out there. They sat on the runway like that for a few seconds, dumbstruck by how bad the wind was. Then Chris called back to cancel their departure, and started to taxi back in.
Marshalls, the operator of Cambridge Airport, has invested recently in some works to the main (hard) runway. This is a bit of a boon for the larger commercial airplanes that fly in and out of Cambridge, but it has been a bit of a nuisance for the Flying Group. The new runway surface is raised 20 or 30 cm above the level of the grass, so where the taxiways cross the main runway, there are ramps on either side. You have to be very careful to line up with the ramp properly when you cross.
The Tiger Moth's tail skid, which is connected to the rudder surface.
Now, one of the reasons the Tiger Moth's wind speed limit is so low is because of how hard it is to control on the ground. The main steering mechanism is the tail skid (shown right), which is hard and digs into the soil as you go. Obviously when you're on a hard surface, it doesn't dig in, it just slides around. "Weathercocking" is a big problem on hard surfaces: if the wind blows you from the side, it tends to push on the rudder surface, and it turns you into wind like a weather cock.

By now I expect you've already guessed what happened when Chris got onto the main runway while taxying back. The wind, which was beautifully straight down the runway, weathercocked the aircraft into wind. Even with the rudder hard over, Chris couldn't keep the aircraft in line with the ramp, and on the smooth surface, he couldn't slow down either.
The Tiger Moth kept sliding forwards, and only just missed the ramp. After recent rain, the ground was very soft, and one wheel sank into the mud. The engine was still running, so the tail lifted off the ground, leaving the two pilots up in the air looking down at the propeller. For a moment it looked as though it might tip far enough for the propeller to hit the ground, which would destroy the propeller and damage the engine. I don't think Chris or the instructor breathed for a few seconds, but they could let out a sigh of relief when the aircraft stopped pitching, and the tail gently touched down again.
However, the ordeal wasn't over. They were still stuck in the mud, and now they were obstructing the main runway. The instructor immediately removed his harness and got out, to try to help shift the stuck wheel. Right away, the tower came on the radio, concerned that the instructor was outside the aircraft while the engine was still running. But because he'd had to disconnect his helmet from the radio to get out, he couldn't hear, so Chris had to try to relay the messages to and fro.
Chris shut the engine down, and joined his instructor at the offending wheel. Even the two of them couldn't move the aircraft, but right away help arrived, in the form of the airport's Rescue and Fire-Fighting Service (RFFS).
Any sizeable airport will have its own, dedicated RFFS, on standby at the airport for all of its operating hours. I don't know if this is true everywhere, but the ones at Cambridge don't have a lot to do, so they like to come out for any unusual event, however minor. And who can blame them? If they did the opposite we would be quick enough to complain. In this case, it was less than a minute before the big, red fire engine arrived and disgorged half a dozen fire-fighters, all grinning from ear to ear at the sight of the little yellow airplane stuck in the mud. With all this manpower at hand, they were able to lift the aircraft (it weighs a little over half a metric ton "dry") onto firmer ground, and they pushed it back to the hangar.
So in the end, nobody was hurt by this little mishap, and the aircraft was undamaged. He didn't say anything, but I think Chris was a little shaken by it. Once the Tiger was safely in bed and he was back at the Group, he was offered a "stiffener" to help recover. After that, there was an incident report form to fill out, and lots of people reassuring him that it wasn't his fault.

That last point is an important one. These things happen, and though I've done my share of taking the mickey out of Chris afterwards, it's because it wouldn't occur to me to blame him for what happened. There's a reason we don't go out in high winds, and the risk of this kind of mishap—or worse—is exactly the reason. Coming back in when they got the wind report from the tower was the right decision, and their little adventure is one of the better outcomes they could have expected.
There's also the legal position, though I'm sure that won't count for much in anybody's head. Legally, the instructor is the commander of the flight, and whatever happens is his responsibility. In this case, it was his decision to go out in borderline weather conditions, so if anyone is to blame, it's him. But even then, we can't know the future: we just make the best decision from the information available. I'm sure if he'd had even a suspicion that this would happen, he wouldn't have gone out, so I don't think blame is very appropriate there either.
Gossip being what it is, everyone in the Group had heard about the incident within a week. I don't think anyone who heard the story did so without thinking, "I'm glad that wasn't me." And I think that's why we all know Chris isn't to blame: it could have been any of us on the day. We're just not sure if we'd all have got away with it like Chris did. We have procedures and rules and limits, but shit goes foul sometimes no matter how well you plan.

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