Look Ma, No Airspeed!

Improving aviation safety for Mooney pilots

Jerry Proctor

(Previously published in MAPA Log)

An experienced Mooney friend provided the material for this article; it is sort of an old classic but well worth reviewing.  I won’t use his real name, but let’s call him Jack.

Jack has an 11 year old Acclaim.  He has owned it for a couple of years and he is also an experienced Mooney pilot having flown and owned other models.  He had to take his plane to a Mooney Service Center as there were some issues with his turbo wastegate and a minor fuel leak.  The service required some new parts and the plane ended up being at the MSC for three weeks before it was ready for pick up.  Jack had a friend fly him to the MSC and the paperwork, payment, and logbook entries took a little time so, in between, he inspected the work and did his preflight.

It came time when all was in order and Jack prepared to depart.  It was pretty much a CAVU day but he filed IFR anyway, preferring to fly home that way.   The MSC mentioned to him, that he should watch the manifold pressure on takeoff, to see if there needed to be any adjustment to wastegate setting.  If so, he could just land and get it adjusted before he flew home.  Jack told me that the start and run up were all normal.  As Jack was cleared for take off and given initial heading and altitude, he applied full power, quickly glanced at the airspeed indicator that was alive, but focused mostly on the manifold pressure numbers.  As he quickly accelerated down the 4500’ runway, he was satisfied that the MP was fine and then he looked over at his airspeed.   WHAT THE…??  The airspeed was showing only 35 knots!  Before he had another thought, he felt the plane lifting off the runway.  It was obvious something was wrong but the power and plane seemed fine, he didn’t even consider aborting and proceeded to climb out.

Well, all of us have had some level of airplane issue, and we also will likely admit it takes a second or two to sink in and longer to figure out what is the problem.  Pitot system obstructed, OK now what?  So Jack called tower and asked to remain in the pattern stating he has a little issue.  The tower said roger and asked if he needed any assistance.   Jack replied no, not yet anyway.  While on downwind Jack hoped he just had water in his pitot tube so on went the pitot heat.  It was a long shot and it didn’t take long to see that was not resolving the issue.  Ummm, OK next, what the heck, let’s pull the alternate air handle.  This actually increased the airspeed from approx. 35kts to 45kts, still not helpful.  Jack thought for a second, he didn’t want to drag the gear around in the pattern, so gear handle up.  That was all that went up as the airspeed was below 106 knots and he would have to press the override button.  No, let’s not do that, why complicate things more.  Jack asked for another lap around the pattern, he was running out of ideas other than I’m going to have to land without an airspeed indicator.

So, Jack told me he asked for a bit of an extended downwind.  He put his gear down at his usual position in the pattern; he reduced his manifold pressure to his normal descent setting, and completed his landing check.  He turned base and extended full flaps.  He wanted full flaps on the base to final turn.  He established himself exactly on the VASI and kept his power in the zone for a final approach.  He had asked for the longer runway, it was not available due to mowing, but this approach, well it felt exactly right so 4500’ was more than enough.  He kept emphasizing that the approach felt, looked, and sounded right as the airplane behaved just like a normal approach.  Normally, on short final, Jack goes below the VASI and tries to land closer to the threshold, but not today, shooting for that 500’ mark.  He didn’t want to come up short.  On very short final, he started pulling the power off and started his flair.  Just before touchdown the stall warning voice sounded and he squeaked it in.  Dang, he said to himself; that was pretty easy.  He was about to be proud but then he thought, I only had to make a no airspeed landing because I missed something on preflight.  OK, eat some humble pie.

After shutdown, he discovered that a little mud had clogged the inside of the pitot tube.  After all, how long had it sat outside.  Jack then thought he also could have used GPS ground speed as a reference point as well.  So the learning point here is reemphasizing the basics is always good; but learning something new is just as good or better.  Let’s face it; learning is a very important part of flying for us all.

Time for a Flight Review or IPC, the Pilot Proficiency Program of MAPA SF can get you there.  We hope to see you there soon!