instrument failure

[bugchaser]

Obviously, you would not want to be in IMC without an airspeed indicator, but do you really think that it is that big of a deal in vmc? Anyone with any experience should be able to safely fly an airplane like a 172 without reference to the airspeed. I know many of you may consider it dangerous or reckless, but I can tell you that airplanes are flying every day without working airspeed indicators. I honestly couldnt tell you if the thing worked or not for the last few thousand hours of ag flying I did. I simply never looked at it. To have people abort a takeoff in a 172 for a faulty airspeed indication is probably more dangerous than just flying the airplane around the patch and landing. This is why there shoud be more emphasis put on learning to fly by feel and not just looking at the airspeed and blindly following it. It is much more common to have a partial blockage that often is not detected. In this case the student or pilot accustomed to relying too heavily on the a/s will attempt to follow the proper speed without having any idea what is going on. Don't all you cfi's make your students fly at least one flight with the indicator covered? Definately not an emergency in vmc conditions.

 

[Tired Soul]

You did the right thing.
However the airplane does not fly by virtue of the airspeed indicator.
Certainly in a plane like a 172 you can fly without just fine if you've had some prior exposore to it.
That's why I do several flights with my PPL students with airspeed and/or altimeter covered up.
If it's not safe to abort, continue.
If you notice in time ( all green, airspeed alive, rotate 65..) by all means abort, but it's not always the right thing to do.
Feds are not gonna get you for returning with an inop airspeed indicator.
For one thing they don't know when it quit, other then what you tell them.
Not advocating anything, but it always quit in the air..
Don't bother with a NASA form.

 

[Immelman]

I disagree for VFR in that I don't think (in a spam can 172) that airspeed is critical. You should be able to make it around the pattern without it and good job on doing so!

I think the go-no go decision needs to be made on a case by case basis depending on runway length, when the problem presents itself, etc... sort of like going nuts over having a door pop open on takeoff... if you can safely abort do so, but don't get hung up and distracted on it, or react to abort when questionable space is available to get stopped.

I actually did lose the ASI once in a Traumahawk on my 3rd solo flight. I hit a bee just as I was rotating for takeoff and the airpseed went up and down from 0-40 knots for a few seconds before settling down at zero. I flew around the pattern and elected to fly just a bit faster approach than normal. I was glad that my CFI had me do pattern pratice once or twice with a kneeboard covering all basic 6 flight instruments!

 

[avbug]

Quick self confession with a couple of stories to boot...

When I obtained my intial flight instructor certificate it was a long drawn out process. When I left the FSDO, I walked outside to the airplane I had rented for the test, and breathed a sigh of relief. I had just flown with an inspector, knew the airplane had fuel and a very thorough preflight and postflight. I jumped in, got my clearance, and took off.

I was coming from an ag background, and that's largely feel, very much eyes-outside-the-cockpit type of flying. I was about fifty feet in the air before I glanced at the ASI for a peek, and noticed it was zero. A quick glance at the pitot tube confirmed that the tennis ball I had placed over it during the postflight was faithfully in place. Amid the satisfaction of having completed the checkride for the new certificate was the humbling self-reminder that deep down inside, I'm really an idiot.

I had lots of runway ahead. But I was in the air. It was clear, VFR, and it was a light airplane that didn't really care if the ASI worked or not. I flew home and removed the tennis ball behind a hangar before parking back at the rental facility. Attempting to land on the remaining runway would have been risky vs. continuing with what I had. The real issue was that while this had just been a minor annoyance it could easily have been a real problem....then again, 61 passengers and nine crewmembers died on Aeroperu 603 in October of 1996 when workers washing the aircraft failed to remove tape from the static ports...little things become big things.

At the other end of the spectrum, a week ago I wasn't looking at the airspeed indicator as I pushed over a cliff into a narrow canyon. I was focusing on a burning tree half way down the cliff on the other side of the canyon. I retarded the power to idle and used a lot of left rudder and aileron, and forward stick to keep the target tree off the nose as I entered the drop. I felt a very violent shudder and then a buffet, and I would have sworn that the left wing was about to separate. A very loud rumbling and shaking occured, all the panels on the side of the fuselage began slamming, and the stick locked up. A red mist of retardant began swirling up from under the aircraft and the nose began coming up. The top of the wing got coated in retardant, as did the fuselage and cockpit, and I cleared the cliff on the other side of the canyon by a reasonably small margin.

I experienced a regime I hadn't been in with that airplane before; it as a high speed stall. It during the event, it loaded the retardant hopper enough that it forced the doors and dumped half the load. I never touched the trigger. It was very loud, very violent, and the stick was locked up with little effect from my input.

The point of that was the airspeed shot a lot higher than I had wanted it during the dive, but I wasn't watching it. I was watching my target, and once I cleared the ridge line to drop into the final run, the upslope wind that I'd felt on the run-in died, and I fell right out the bottom. My first clue, being oblivious to the wind noise and being far too focused on that tree, was sensing sinking into the canyon...all the rocks began rising in the windscreen instead of staying put, and when I did try to pull, the aircraft wouldn't recover. I flew out because the loading in the diving turn forced the retardant out by overpowering the tank doors...I had nothing to do with it.

The point, again, was watching airspeed can be pretty darn important, and failure to do so can be costly. Little things become big things. You probably weren't going to run into that much drama flying the 172 home, but you were right to take notice and handle it as you did. Noticing sooner would have been better, but you made a good decision to continue the takeoff when you did, and a good decision to come back and land.

 

[coolyokeluke]

I once hopped out of an airplane and went directly to the next student. A fellow CFI had asked me to fly with his student, he'd told me this student was on the verge of soloing. He had the airplane preflighted in front of the avionics bay. That should've been my first hint. Everything was normal until we were about 200' AGL, then the airspeed began decaying even though our pitch attitude and power were constant, and the altitimeter froze. While in the pattern I emphasized how the student could fly the airplane usings known power settings (and sound of the engine), pitch attitudes, and his outside references. We made an uneventful landing and sure enough, there was tape over the static port. In hindsight I could've pulled the alternate static air source, don't know why that didn't occur to me. I had a conversation with the student about CAREFUL preflighting and we both learned a lesson.

 

[dhc8fo]

In 121 world, that is an abort..no questions asked.

In 91 world, it is judgement call as others have pointed out. I had this on my old Cherokee and decided to convert the flight from a pilot-brushing-up flight into a pilot-investigating-something-that-needs-to-be-fixed flight (it was VFR and I was alone at an uncontrolled field with a short runway).

As others mentioned, flying without the A/s indicator is hopefully something you did in your training (sounds like you did a good job). If any of you others haven't, make sure you try it. Forces you to pay attention to pitch attitude, RPMs, and the varying noises from your plane in different configurations. Good stuff.

 

[Bryan D]

Anyone thats ever flown a SuperCub will tell you that an airspeed indicator is not needed. It called flying by the seat of your pants.

 

[JediNein]

the humbling self-reminder that deep down inside, I'm really an idiot.

All I want to know is why do those reminders come so quickly after an accomplishment?

 

[cforst513]

flying the pattern and landing with no A/S ind wasn't a problem. i came in just like i normally do, just had to float in ground effect a little longer to bleed off the excess airspeed. a citation took off when i was on final, so i potentially had wake turbulence to deal with, too, but i wasn't airborne when i reached the point where they took off. i made sure of it.

as for the NASA form, i didnt' break any regulations, did i? my instructor and an assistant chief both said not to worry about it. should i do it just in case, or would that be overkill since no metal was bent, no one was injured, and (to the best of my knowledge) i didn't break any rules?

 

[JimG]

I had this happen 18 years ago in my Bonanza.

It was VFR, but at nightime on an instrument lesson over a dark desert away from the city lights.

The preflight was in the dark, and neither I, nor my instructor (although it wasn't his responsibility) noticed that someone had helped himself to my pitot tube.

It was an uneventful return to the AP.

I make sure I physically touch that thing EVERYTIME I do a preflight now.