Wake Turb recovery in NZ - Push to unload?

[Wombat35]

Hi,

Reading the latest crash comic I was surprised at the "Push to unload the aircraft" recovery for wake turbulence....

I quite often pass through wake turbulence at AR, given the correct conditions, and advise my students to aim past the touchdown point of the preceding aircraft (add power and move you aim point) or if you cannot due to strip length, then go around.

I feel the key in a GA aircraft is to climb above it if possible. Possessing an ex mil background, I was not instructed to "push to unload the aircraft" except when seeking maximum acceleration to get away from the bad guys.

Is pushing to unload the aircraft the best approach at 200AGL? Imagine reading this article if you are a PPL with 100hrs or so.... is this the best advice we can come up with....?

Interested in other GA pilots thoughts, as I’m just getting back into GA and maybe I'm missing something... There seems to be nothing about this in my CAA instructing notes and I'm wondering if this is the "approved recovery" method then surely it should be in the CCT briefs... or perhaps somewhere?

Cheers

Wombat

[Runaway Gun]

I hate to think that many GA instructors actually have a vague understanding of unloading, it's affect on acceleration, AoA, and on the stall. It might also brown-streak their daks.

I'd also hate to be in the left hand seat when said instructor decides to try it on for size at low level !!

Going around is sure to be the safest method.

[MOR]

As I said in another thread, the advice given on recovery is nonsense. This information contains the rider "note that this technique is primarily designed for wake turbulence encounters for aerobatic aircraft manoeuvring in tailchase or dogfight conditions." WTF does that have to do with GA? The methods suggested could be quite dangerous for inexperienced pilots, particularly when you consider that earlier in the article, we are told that most wake turbulence encounters take place in the takeoff or landing phase, below 200'AGL. Nowhere in the article is there any advice on what to do if you encounter wake turbulence at low level during takeoff or landing, in a non-aerobatic aircraft with limited power.

When you actually encounter serious wake turbulence (ie behind a medium or heavy aircraft), the most common symptom is a rapid roll followed by a climb or descent. The priority is to get the wings level and maintain control. On approach, you shouldn't encounter wake turbulence unless you are well below the nominal 3 degree glideslope. Moral - be careful about making short approaches or going for the first turnoff!

You aren't missing anything Wombat, the advice is just plain bad (not to mention innapropriate for GA).

[Speeds high]

you shouldn't encounter wake turbulence unless you are well below the nominal 3 degree glideslope

MOR, tutt tutt; with your experiance surely you know this old theory to be untrue. NASA did an independent study of wake some years back for Boeing after they got sick of rudder hard over being blamed for every crash.

NASA found that wake sometimes CLIMBED at random, not descended as the vector text would have you believe, also the wake vorticies can persist in tight spirals for more than 3 minutes bursting at random points down the vortex.

[MOR]

NASA found that wake sometimes CLIMBED at random, not descended

Yes, but only under specific conditions that are not common in NZ.

From the NASA website:

NASA research has shown that as large aircraft move through the air, trailing vortices tend to remain spaced less than a wingspan apart while sinking at a rate of several hundred feet per minute. Over time, the sink rate will slow and their strength will taper off. Research has shown, however, that vortices can also rise during conditions of ambient thermal lifting.

Vortices of large aircraft often move laterally at speeds of 2-3 knots when they sink to within 100-200 feet of the ground.

In calm wind conditions, vortices created by large aircraft during landing operations can remain for many minutes over the normal touchdown area. They can also slowly drift from one runway to a nearby parallel or crossing runway.

In other words they will only rise when there is significant thermal activity, and the sort of thermal activity they are talking about is the sort you get in the hotter parts of the USA - not typical conditions in NZ.

A great pity that the editors of Vector are unable to find such websites, which by the way can be found at http://www.nasa.gov/centers/dryden/about/Organizations/Technology/Facts/TF-2004-14-DFRC.html

According to the NASA website, the last WT research was carried out in 1974, so I'm not sure what research you are referring to - do you have a reference? I'd like to read up on it.

[Wombat35]

Well I think I understand where this came from after seeing the Taupo stuff last night on Campbell Live.

If that's the head of my CAA he seem to be old, tired and out of his depth. A great example for the rest of his staff.

Whilst I have no real comment about flying into Taupo as I have only been in there once IFR, I can see that these things seem to come from the top.

I wonder if he read the advice before he released it to the wider community. (and yes I do hold him responsible for what his department releases)

Just yesterday my PPL student (1000+ hours, however new to wheeler landings on a taildragger) tried to fight through wake turbulence at 20' rather than go around. Now he is going to read this article in a couple of days and I'm going to have to explain "no you don't push to unload" even though my aircraft is aerobatic....

:rolleyes:

[On speed on profile]

Wasnt Annette King the minister of Health for a bit. Now shes in charge of transport and the CAA.

We now have someone monitoring a piss poor outfit who has no idea what she is doing.

I dont know which is worse. Having the CAA as it is or having another minister who hasnt got a clue trying to reform it!

If its anything like the multiple education ministers or the multiple helath or MOD ministers. We are screwed!! :eek:

[Capt. On Heat]

Couldn't agree more Wombat. I really do wonder why Mr Singleton (editor) thought Fighter Combat International was the best source of data for recovery techniques in a publication aimed at pilots whose country doesn't even have 1 strike aircraft! Poor CAA, they really are having a bad month. Couldn't have happened to a nicer organization............ :8

[Naughty S]

Last time I experienced this sort of thing I turned around and asked Senator Vanstone to remain seated until the aircraft has landed.