Well, it’s pretty clear, Mr. PukinDog, that you’ve made some interesting points …
1. “Clean" can include anti-ice fluid that hasn't failed/reached its saturation point.”
2. “If its not wet and glossy but turned opaque, and especially if there's snow present on the fluid surface, the solution has lost the ability to melt frozen precip and absorb/suspend/depress the freezing point of the water.”
3. “Unless other procedures have been approved in the Ops Specs, the general rule for U.S. air carriers (121.629) if HOT has been exceeded there must be pre-takeoff contamination check accomplished within 5 mins before T/O, and it must be done from outside the aircraft.”
4. “If the pilot has miscalculated the precip type/intensity or other variables came into play (rapidly chancing temp/wind/jet blast) that cause visual indications the fluid has failed within the HOT, the pre-takeoff contamination check from outside the aircraft within 5 mins must still be done.”
5. “Since the manufacturers of fluids do not give a holdover times for heavy snow conditions, it did use to cease t/o operations because it threw Type 4 HOT tables out of whack, but now it's allowed if it's applied at 100% strength and a "definitive fluid failure determination" made within 5 minutes of takeoff.”
It’s a shame that the crew of that accident airplane in January of 1982 were not aware of the kinds of things regarding airplane operations in icing conditions you listed. However, I would point out, for your careful consideration that most (if not ALL) of this information, these recommended practices, and these scientifically derived experimentation results you just provided were gained a result of the examinations, experimentations, arguments, discussions, decisions, and considerations conducted because there wasn’t sufficient information on these issues very readily apparent, or even available, prior to this accident? In fact, you used the term “hold-over time” (or HOT, the now-easily understood reference) but I would remind you (and all who are reading this) that, at the time of this accident, these terms, these facts, this information … was not very-well known by flight crews … not even by many of the folks that worked with and ultimately developed the solutions that were to be applied to ice-coated airplanes.
Look … I’m not here to “bust your chops” or insult the very professional aviator that you likely are. I’m only trying to show that the often misunderstood causes of this very specific accident were then, and still are, at times, just that … misunderstood. I’m not accusing anyone of any ulterior motive … I just want all of us to understand that there was a lot of pressure, from all sorts of positions, to get this accident resolved and move on! Just like anything that has negative consequences, those who knew more, or should have known more, are in the cross-hairs. It’s easy to spread the blame … I’m not looking to fix the blame on anyone … in fact, I’d much rather fix the problem than fix blame … and, to a very large extent, a lot of those problems have been very adequately addressed … at least I certainly hope and pray that they have been. We can’t ask the crew what was really running through their minds when they were commenting on other airplanes’ exhaust was apparently blowing onto their airplane. We can’t talk to the other Air Florida pilot (I apologize that I cannot remember his name) who was aboard, and was seated in the exit row window seat on the LHS of the airplane throughout this whole process. Why was he comfortable with what he was seeing outside his window … heck, did he even look outside his window? We can’t go back and ask the F/O what it was that caused him to question whatever it was that made him say what he said. We can’t ask that Captain why he did not elect to abort the takeoff. We don’t know why the deicing truck was “repaired” the way it was. Did anyone know that doing so would affect the results of its use? Why did the controller feel it was “OK” to clear an airplane for takeoff when there was another airplane on final approach well inside the FAF knowing that the visibility was as poor as it was? We now know these things and I would suspect that no one does them any longer. But the fact remains, they were done at that time. With what we know now, there are a lot of changes that have been made to a lot of “routine” process that are accomplished by flight crews on a daily basis – and that is a VERY good thing. We no longer “set power” by reference to the EPR gauges and then scan the instrument stack for symmetrical readings … we look specifically at the indications of the rotor speeds – noting the specific RPM percentage indicated. We look specifically at fuel flow – noting what the gauge actually indicates. Pilots do this routinely today – not just during inclement weather takeoffs. We are (at least generally) a lot more sensitive to where the engine exhaust is directed when we begin to move the airplane. We are a lot more careful about how closely we follow preceding airplanes on the taxiways. We are much more observant about the deicing process – we are more knowledgeable about the actual solution of glycol in the mixture being used to deice our airplanes. We know a lot more about “hold-over times,” and what compromises those times … and what must be done if they are compromised – if not by regulation – then by company – or personal – procedure. I think the professionals that manage the traffic at our airports are a bit more aware of how quickly landing traffic can get to the end of the runway – and how long pilots usually take to spool up, check what they want to check and set the “stuff” the way they want it, BEFORE they release the brakes for takeoff. All good things.
I just wanted to “set the record straight” - or at least “straighter” - than it is typically understood.