Monday, July 20, 2009

Vwhy - Vwhynot

Summary: airspeed is a critical resource on go-arounds, touch and gos and IFR missed approaches.

When leaving the runway environment, airspeed is a critical resource. This is a no brainer when doing take offs from a full stop, but for some reason, many pilots unnecessarily let airspeed decay when conducting a go-around or touch and go by not adding take off power immediately. When deciding to climb in a draggy configuration (flaps down, gear down) it is important to immediately add power, then clean the airplane in order to minimize airspeed loss. In one extreme case, I was with a pilot doing a touch and go on a short runway who spend what seemed like an eternity looking for the flap switch, then he radioed tower to let them know he was going around. I am sure it was obvious to the tower a go-around was in progress. First fly, then talk! I teach my students that if you are not flying safely you have no reason to be talking unless perhaps it is a directive to avoid a collision. Do not be afraid to use the term "stand by" if your are in a heavy workload dealing with an "aviate" problem. Controllers will know that you are busy and will get back to them as soon as workload permits.

I teach the 5 C's which I learned from my instructor. Note the adherence to the all important priorities: aviate, navigate and communicate in that order:
  1. Cram it. Don't stab the throttle - be nice to the engine, but don't wait either).
  2. Climb it. When the flaps are down and the pitch is trimmed for landing, this means push on the yoke to prevent a trim stall. Eventually you will want to attain a balked or a short field airspeed, followed by Vy.
  3. Clean it. Reduce flaps to manufacturer's balked landing setting or the setting used for short field take offs. Memorize your balked T/O or short field airspeed and keep this speed. Do whatever your AFM says about flap vs. gear up order - memorize this!
  4. Cool it. This usually means open cowl flaps if the airplane has cowl flaps.
  5. Communicate it. If this was an unplanned go-around, let tower know.
If you not aviating and navigating, you should not be talking. Never tell tower you are going around after being cleared to land until you have completed items 1-4.

Regarding IFR missed approaches, the 5 Cs apply with one twist. Upon reaching Vy, maintain it until you are absolutely positive you are clear of the highest obstructions within a conservative distance of the airport. (Study approach plates, VFR charts, MSA values, etc. for the lay of the land before your flight.) After this point, pitch the nose down and attain a cruise climb speed. At all times your climb rate must meet, preferably exceed, the minimum required climb rate for the missed approach being executed until reaching a specified level off altitude.

A mistake I see IFR pilots make frequently when executing a missed in the muck is a tendency to cram in full power, but not pitch up to attain Vy afer cleaning up and in a fast airplane this leads to a lot of scary horizontal, rather than climbing flight. Remember altitude is your friend. Once the decision is made to execute the missed, not only is it important to have memorized the first few items on the missed approach, but it is equally, if not more so to execute the 5 C's first with emphasis on attaining a Vy airspeed as soon as safely possible.


Propeller Bending

Wow, was I wrong (this is the first mistake I have ever made :-).

Propeller bending as shown in the picture below is an artifact that has something to do with the way digital cameras capture images and is not really due to the prop bending. At least not all the bending you see in the photo is real propeller bending.

Thanks Andrew for the education.

Some bending does occur, but not as much as my digital camera indicates, and this is what makes prop edge dings so dangerous. Think about steel wire. With a file make a small score perpendicular to the wire's axis. Start bending the wire. Where the break will occur? At the score. As a kid, I worked on farms, this is how I would cut fence or bailing wire that was too thick to cut with pliers. I used the cutter on a plier to score the surface, not cut it, and bend it back and forth until it broke. Think of a ding then as a stress point that over several bending sessions could lead to a propeller break. AOPA says that if a ding (also called a nick) is less than 1/32" wide or deep it can be deferred to next maintenance. However, I say that if an AP is nearby holding a file in his/her hands - why not ask? :-)