Practice Frozen Pitot Tube?

[squeakmail]

I've just read a three page article - in a magazine called "Aviation Safety' - where an "instrument" flying instructor (who holds an ATPL) suggests two training ideas.

1) Leave on the pitot covers or cover the airspeed indicator and practice doing take offs and landings with no IAS reading, and

2) Flying (in good VMC) into known icing conditions in a diliberate attempt to pick up pitot icing - thereby learning the indications of a frozen pitot tube.

Any comments? Either for or against. Would you like me to re-post this in Jet blast so that you can say what you really think?

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LIVE in peace...or REST in it!

[Islander Jock]

I am not an instructor but for my money why not just use the good old circular instument cover over the ASI. Those round soap holders with the small suction cups on one side are excellent. No need then to fly around with a deliberatly blocked pitot tube which would probably be illegal anyway.

In regard to the icing issue, If I was the trainee, I'd only like to see it contemplated with dual AS, and pitot heat systems so that at least the R/H side could be relied upon. And while your deliberately building ice on your pitot, what about the buildup on the windscreen and rest of the airfame?

In short, why do it at all? Provided pre flights are conducted correctly, including function of pitot heat, then the chances of icing in the system should be almost removed completely.

Also, are you risking giving the basic student, assuming that is your target audience, a little too much info and therefore giving him/her a false sense of security. "I've been in icing conditions before. I'll know how to handle it".

I recall one dummy landing one day and coming over to me and asking "How much ice is too much" and this was a CPL holder who deliberately flew his VFR piece of crap into IMC.

[Diesel8]

Now, why would you have to fly into icing conditions to learn what a frozen pitot tube does. That could easily be explained on the ground, no airspeed indication(drainhole not blocked) or no airspeed changes when level even with large power changes ( drainhole blocked).

Covering up the ASI is also a perfectly good way to teach and basically covers the same idea, much the same way we teach instrument failures to I/R students.

I used to cover up most of the instrument panel when teaching private pilots, leaving for example the tach and altimeter available, this of course to teach them how to fly the aircraft by looking outside and by how the ac felt.

[DB6]

The phrase 'flight into known icing conditions' springs to mind. Just don't look at the ASI. That way if there is a problem you don't have to uncover it at low level on final approach.

[ianh]

Covering over the instrument is ok, but I would certainly not condone leaving the pitot cover on.
As for flying into known icing,apart from the practicality of doing this and remaining VMC( the two tend to be mutualy exclusive),
I can only say that this is probably the most foolhardy suggestion I have seen on this forum!!

[This message has been edited by ianh (edited 23 December 1999).]

[Robbo2Alpha]

I cannot believe an instructor would condone such a diliberate act of sabotage! Cover the instrument by all means, but that is all that is required. BTW Islander Jock, try not to use those little soap things, they leave a plethora of little pock marks and through time affect the clarity of the instrument, and the engineers hate it, enough reason in its self!

[Islander Jock]

Robbo2Alpha,
Thanks for the advice mate. Better tell the wife. She keeps a couple of 'mankey' soap holders in her headset bag for those impromptu limited panel sessions.

[britavia]

How about when it happens in reality in actual IFR? Now that is interesting!

[squeakmail]

Darn it...I use manky soap dishes too...bloody useful (but they do keep falling off when the spit dries)..anyway...

I'm surprised no-one has commented on the suggestion that a student be taught to continue a take off when the ASI is not playing fair. If we are going to learn the "attitude and power setting" required to continue a take off then why bother with the "T's & P's in the green, airspeed alive" check. If we are going to ignore the indications anyway - we may as well omit the check (less to get wrong?).

I can see my way to agreeing with "attitude and power setting" for pretty much any other flight exercise..but "take off" - would any one of you consider continuing a take off if you even suspected the ASI was faulty before the point of rotation?

At least we all seem to agree on the "flight into icing" aspect - wonder what his insurance company thinks about the article?

[Irish Steve]

Hmmmmmm.

Deliberately take off with the Pitot covered? Not a good idea, while in theory nothing ever goes wrong on a well maintained aircraft, I don't think I'd be too happy if something else chose that trip to go U/S.

I'd been flying a Seneca for the better part of a week with no hassles, and on my ME check ride, the RH Vac pump went US on us. What made it "interesting" was when the examiner then shut down the left engine to do the single engine stuff, and a couple of minutes later it was "relucatant" to unfeather, as the oil was still too hot!

So, the idea of having something that's working deliberately inoperative in a manner that can't be changed in flight looks *very* suspect to me. By all means cover the ASI, and any other instrument, at least that way, if things suddenly change in an unpredicted manner, there's a way back. The other thing about a covered Pitot is that in some cases that may also lead to inaccuracies of both the VSI and the Altimeter, depending on where the Static port is. The more I think about it, the less I like the idea!

Deliberately flying into known icing in an aircraft that's probably not cleared for it sounds like a good way to end up dead. Not to be recommended!



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"Irish" Steve

[Hugh Jarse]

How bloody stupid and negligent is that so called "instructor"?? Fortunately most instructors will see through such a foolhardy suggestion.

Personally, I use(d) a specially treated plastic (susceptible to static electricity) to cover the various instruments for lim panel. No sucker marks! All you do is charge it by rubbing briskly on clothing (trousers or similar) and it sticks for ages.

[squeakmail]

Originally posted by Hugh Jarse:

Personally, I use(d) a specially treated plastic (susceptible to static electricity) to cover the various instruments for lim panel. No sucker marks! All you do is charge it by rubbing briskly on clothing (trousers or similar) and it sticks for ages.[/B]


....and where do you get them from, Hugh?

[Dan Winterland]

How about 'Post-it' notes. I carry them in my nav bag for things such as call sign reminders, and covering up instruments if they fail. I used to use them when I was an instructor on my unlucky students.

Also, I used to instruct on an aircraft that is regularly spun inverted. Before they put a restrictor in the pitot circuit, the pressure pattern around the aircraft used to surge the pitot pressure and wreck the ASI. this happened to me twice. The first time it happened, I got a b*llocking for not getting a formation approach from another aircraft. The second time, I got the formation approach, but it really wasn't necessary as it really is in the capabilities of most pilots to be able to fly an approach on attitude and power settings alone, especially if you have a stall warner. Think back to the attitude required to stall in the approach configuration.

[Capt Homesick]

When I was a student, I had this on a test- the instructor carefully covered the ASI, but angled the cover so that he could still see it. Not only is that safer (even though we can all, as experienced instructors, fly reasonably accurately without it, with good safety margins), but it gives us the chance to assess the student's accuracy objectively.
Something like the limited panel covers used in CAP509 schools is ideal- securely held in place, preferably in a way that will not degrade as it ages.

[squeakmail]

Please...somebody put me out of my misery...am I wrong here???

How can we justify accepting the comment "practice take off's with the ASI inoperative". ????

[Hugh Jarse]

Sorry Squeak, but the stuff I have was issued by the company I was working for at the time.

BTW manoeuvres involving malfunctions described above should be left to the simulator (if possible).

Two questions you have to ask regarding (continuing)takeoff with the pitot obstructed is:
1:What is the practical significance of such an operation?

2:What is the expexted learning outcome for the student?

Perhaps someone could answer that for me....

[Wee Weasley Welshman]

I am in the habit of doing partial panel with any PPL students that I have taught for most of their course. With the good ones I even do it with the foggles on. Nothing too hard but I find that if you make them fly and approach with the ASI that:

a) it can be done safely and

b) they gain a great deal of confidence from it and also

c) they learn to use their ears and seat of their pants

I would never induce an actual failure in any cockpit instrument. Obviously.

WWW

[Capt Homesick]

The only reason to continue a takeoff with an inoperative ASI that I can think of is:
in a 2-crew aeroplane, if the NHP calls speeds from his own ASI without cross-checking the HP's side.
Initially, the HP is busy looking out the window, and by the time he looks in at his ASI, they're past V1.
But in that case, you'd still have a working one anyway, so it's still not a good idea...

[Diesel8]

Most light airplanes will have ASI movement at like 30-50 kts, so if no airspeed one can easily, and should, stop and investigate. Certainly a check of engine gauges and instrument gauges should be part of the takeoff routine during the roll once full power has been set.

In our company, two crew AC btw, we do a crosscheck at 100 kts, NFP checks both ASI and calls 100,FP checks his and calls checked.

[This message has been edited by Diesel8 (edited 31 December 1999).]

[straight&level]

I agree with comment above.
My company teaches 1.power satisfactory
2.T's and P's green
3.ASI alive
'continue the take off'
If the ASI is not alive abort.
On the other hand when airbourne covering the ASI is very useful and will certainly reinforce the concept of
POWER + ATTITUDE = PERFORMANCE.

[Capt Homesick]

Diesel, I'm worried, I find I agree completely with you! http://www.pprune.org/ubb/NonCGI/eek.gif

[Diesel8]

Capt.Homesick:

It is my most feverent hope that this is merely an aberation of nature and that it will only happen once a millenium.

(Tongue in cheek) :)

[squeakmail]

sorry...ignore this...just testing a problem I have.