Unserviceable ASI??? Errrrm.....

[Maarten]

Just to amuse you guys and gals with a little story of my stupidity.

Yesterday, TWR had given me clearance to taxi to the holding point, which at my base (Manston) is one heck of a long taxi. As a result I tend to taxi somewhat faster than the walking pace I know I should be maintaining.
During the turns I checked the correct movement of all the relevant instruments and all was working well. On the long straight run down to the holding point however, I noticed that the ASI was firmly stuck on zero despite the excessive taxi speed. Stopped at the holding point to ponder on this for a moment and, as the pitot heater cover was definitely in the pouch behind my seat and not on the pitot tube anymore, could not think of anything clever so I called TWR to request taxi back to the flying club.

The moment I started taxiing the ASI jumped into action and it was only then that I realised that the wind speed must have exceeded my taxiing speed on the downwind run to the holding point.

Clever, isn’t it?
:D :D

[tacpot]

An excellent post. Well done for figuring it out so quickly!

[FormationFlyer]

:D

Now you arent going to tell me it was 20G30 are you?!?!? :eek: ;)

[sennadog]

Cheers. One for the memory banks.

[Maarten]

Now you arent going to tell me it was 20G30 are you?!?!?

Are you serious!! You didn't spot the hurricane that hit the South-east on Wednesday??????:D :D :D :D

[Carlito]

That's why I do take off check during the take off roll. "Airspeed indicator alive" If it doesn't come alive pronto, take off is aborted.

Interesting point. I was only thinking about it today after flying approaches in different configs, Clean, Flap, full flap short field etc. In each case the approach airspeed is different. How the hell would you manage to land with an U/S ASI? The "look and feel" of the aircraft?
Carlito

[tacpot]

Carlito - the theory is that if you set a known power setting and set the aicraft up in a known configuration, and maintain a fixed attitude and you will acheive a fixed (safe?) airspeed. So the problem of speed control become one of precise attitude management.

In practise I know that I would find it very hard to land off an approach without an ASI.

But having thought about it, our 'safety net' is the stall warner (or other stall indications). If you're getting the stall warner, then your attitude is wrong! So you carry out a standard stall recovery and if there is height and space to continue the approach you do so, otherwise you go around, and try with a lower nose attitude.
:eek:

[411A]

Interesting to note that airline crews, as part of the normal scan during the early part of the takeoff roll, check for proper ASI indications...some companies have a required call (airspeed alive, for example).

In addition, during certification, the flight test pilots demonstrate various combinations of weights, body angle and power settings to achieve proper airspeed control without reference to the ASI, with and without the radome installed.
These are published in the AOM for crews reference (transport catagory aeroplanes).

For your own information, have a look at the ASI and the power setting used to achieve a normal 3 degree flight path descent to the runway and file away for future reference. Could be useful some day.

[FlyingForFun]

Could I suggest that anyone who isn't sure how to do an approach without reference to the ASI goes flying with an instructor, and gets the instructor to cover up the ASI?

One of the instructors I used during my tailwheel conversion was very big on making me not look at the ASI during the approach. I was in a Super Cub, with the instructor sat behind me, so he could see my head move down to look at the instruments. He claimed that, on a perfectly good approach, every time my head moved down, it was followed by me changing attitude and screwing things up.

It took a lot of effort to break my old habits, but once I got the hang of keeping my eyes out of the aircraft, landing the Super Cub became a whole lot easier! Just set the power, set the attitude, and then fly the attitude all the way to the flare. The danger if you're looking at the ASI all the time (and the mistake I was making) is that you're constantly chasing the airspeed, making small attitude adjustments to try to keep the needle where you think it should be. This results in a less stable approach, and it's much harder to judge where you're going to touch down, and to flare properly.

And it has the added benefit of meaning you know what to do if your instruments do fail!

On a related note - during my night rating training, my instructor would frequently turn off all the cabin lighting to simulate an electrical failure. This made it impossible to see any of the instruments, and I would fly the entire circuit only by reference to features outside the aircraft. The only instrument I missed was the altimeter. Although, with a little bit of practice, I was soon able to judge roughly what 1000' looked like, and could get it to within 50' most of the time. Doubt I could do it now, though, because I haven't practiced it!

FFF
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[Aerobatic Flyer]

Could I suggest that anyone who isn't sure how to do an approach without reference to the ASI goes flying with an instructor, and gets the instructor to cover up the ASI?

Last year I had an ASI failure while on an instructional flight - at any speed below about 90 kts, indicated airspeed was "very slow and variable"....

The instructor decided that that was the day to get out and make me do 3 solo circuits at Meribel altiport..... Meribel is a bit on the short side, and definitely somewhere where you'd think an ASI would be essential. Funny thing is, I landed more accurately than ever I do with an ASI! :rolleyes:

Not having an ASI definitely heightens your awareness of everything else.

[Centaurus]

There is no "rule" which says you should never taxy at speeds exceeding a fast walking speed. That is a myth which had its origin in tail-wheel types not fitted with brakes - Tiger Moths for example. Commonsense dictates that you adjust your taxying speed commensurate with aircraft type, pilot experience and the local environment.

The myth does have its advantages of course in that compared with the airborne segment of the flight the engine on, to engine off, time is longer and the instructor and aircraft owner get more money in their bank accounts.