Cross Wind T/O and Landings

[LeadSled]

JT at al,
With the very greatest of respect, I actually know what I am talking about in these areas --- something that Lookleft is unlikely to accept.

I stated in an earlier post that, to determine how Vmcg (or anything else) for an FAA type and variant was established you have to consult the flight test guide for said type and variant.

This is not the same as a text book definition of Vmcg, as I am certain you would agree.

As to "stories" about special DCA "rules" that said a VH- registered aircraft has a Vmcg that ensured it would stay on the runway in the most adverse crosswinds, I heard that quoted many years ago, but never found any proof. Indeed, I never came across anybody in DCA who would have had the background to conduct such tests, and I have no idea what might have gone on at Moses lake with the B707-138A/B in all its variations.

I never flew the B707-138A/B ( along with the RR powered B707-300 the only significant variants of the B707/720 I haven't flown) so there could have been some sodding around with the numbers there, but the certification of Vmcg for the B707-320B/C with JT3B-3D engines with large blow in fan cowl doors was quoted by Boeing as good to 7kt crosswind,--- straight from the FAA guide and from the mouth of one of the pilots on the flight test program --- and the Limitations (mandatory) section of the manual for a VH-registered aircraft was the same as an N-registered aircraft.

The same was (mostly) not true if it was a G-registered aircraft.

Likewise, most of the V speeds for a G registered aircraft differed from the US/AU Limitations speeds. Again, thank that opinionated and short tempered little Welshman -- who did sign my first flight test approval, although, I might add, not Experimental Flight Test, just "post production/maintenance".

"Back in the day", at YMML on a cold and wet and windy (from the WSW) we used to see the "safety advantages" of applying a crosswind component to the Vmcg, when you had a Vmcg limited V1.

I would be able to use RW 27, with a bit of a crosswind.

In contrast, my oppo mate in a BA B747 of otherwise similar model would have to use RW16, because he couldn't use RW27, because of the "crosswind enhanced" Vmcg limited V1 could not be accommodated on the much shorter runway. So he was faced with a significant crosswind, on a wet runway, much longer taxi distances, and substantially longer track miles in the air.

Such was the result of a certified Vmcg being a variable based on crosswind component.

Again, "back in the day", Qantas had some truly excellent people, for those of us with an engineering background (and I don't mean LAME) who had gone flying, there was a wealth of information available for the asking. Some of us made full use of it. I have always been rather sceptical of OWTs and "conventional wisdom", preferring the check the facts.

Indeed, over many years of instructing, I have always made clear to my students the clear difference between "my opinion" --- to hopefully be considered of some value by the student/candidate , and something stated as a fact, and therefor non-debatable ---- I would always give the student/candidate a reference, so they could check the facts for themselves. It was remarkable, at times, how strongly OWTs and "conventional wisdom" would be defended, in the face of the facts.

Tootle pip!!

PS: Were you every involved with B727 -100/200 certification, the V speed "demonstrations" must have been hairraising ---- I am happy to have only read about them.