I had to get checked out in the Caltech Aero Club‘s C172 (N54678) and so, my instructor, Russell Thomas and I decided to do some night flying as part of the checkout. Since I had told Russ that I’ve never landed at Ontario, he figured why not do some pattern work at Ontario (KONT). What a trip!
I decided to take a short flight to Whiteman Airport (KWHP) this last weekend. It’s been a long time since I actually did anything remotely resembling a cross-country flight on my own and, even though KWHP is only 20 miles from KEMT, I thought it would bring back some old memories. I was not mistaken 🙂
As I mentioned earlier, I passed my Private Pilot checkride this week. I’m
really happy that the training that I started, with some trepidation, about
a year ago finally resulted in my getting a Private Pilot’s License (PPL).
I am very happy to inform you that I am now a licensed Private Pilot! That’s
right. I passed my private pilot checkride on 9/11/2012. In my next post I
will write more about my checkride and what it took for me to get here.
Apologies to anyone who has been expecting new content on this site. We were having a lot of issues at work which, ultimately, resulted in Meteor Games laying off almost the entire team on November 30, 2011. I, therefore, have a little more time on my hands right now and will be posting more often.
The very mention of the word “stall” in the context of flying conjures up images of aircraft falling out of the sky, for most people. While stalling is definitely an issue that can occur in an aircraft, all pilots are trained to recognise an imminent stall and take corrective action, or to quickly recover from a stall, should one actually occur.
On the second day of flight training, my instructor showed me what is called an “incipient stall”, i.e. a situation where any increase in the angle of attack, or a reduction in power would result in a stall.
On day two, we actually practiced stalls – both powered and “power off”. So, what’s the difference between the two stalls, and can a stall actually occur when the aircraft is powered?
What is a Stall?
A stall occurs when the “angle of attack” of the aerofoil exceeds what is called the “critical angle of attack”. So, what is this thing called the “angle of attack”?
Angle of Attack
The textbook definition of “angle of attack” is that it is the angle between the chord line of the aerofoil and the relative wind.
In order to understand what we mean by the chord line, let us take a look at the cross section of an aerofoil given in the figure, from Wikipedia, below.
In this figure, you can see the chord line in approximately the middle of the aerofoil (the dashed line). The angle that the chord line makes with the “relative wind” is called the angle of attack.
So, what is this relative wind, you may ask? Let me try to explain. The simplest explanation is that the relative wind is the direction of airflow opposite to the flight path vector of the aircraft.
How does a stall occur?
In order for the aircraft to stall, we know that the angle of attack must exceed the critical angle of attack.
One way to force that situation in flight is for the pilot to slow the aircraft down significantly while holding the aircraft in a substantial nose-up attitude. As the aircraft slows down, its flight path starts to move more and more towards the horizontal, due to the reduced thrust that can no longer overcome drag. In other words, the aircraft is no longer climbing, but is starting to follow a level flight path.
In such a situation, the angle of attack starts to increase until, at one point, it exceeds the critical angle of attack, and a stall occurs.
Indications of an Imminent Stall
As the aircraft starts to get closer to a stall, a number of things occur. First the controls of the aircraft get very “mushy” and unresponsive. The aircraft is in a significant nose-up pitch attitude. In addition, there is a clear reduction in the sound caused by wind blowing against the aircraft. A trained pilot can recognise these signs and take corrective action before the stall occurs.
If the pilot is relatively inexperienced, or is unable to recognise the symptoms, most aircraft are equipped with one or more warning devices. In the case of the PA–28–140, the device is in the form of a red lamp on the dashboard that starts flashing as stall becomes imminent. On other aircraft, there is a siren, or a combination of a light and a siren.
Power Off Stall
The power off stall does not require that the aircraft be powered off in mid-air. Rather, it intends to simulate conditions that may occur when the aircraft is landing.
This means that while you’re flying, you slow the aeroplane down into close to landing speed, lower the flaps and the undercarriage (if applicable), and then start to pitch the aircraft upwards until a stall occurs.
Power On Stall (Full Power Stall)
The power on (or full power stall) seeks to simulate a stall when the aircraft is in the takeoff mode. To simulate this stall, you slow the aircraft down to takeoff speed (close to Vx or Vy), then rapidly increase power to maximum (or 75% of maximum) while raising the pitch attitude until the stall occurs.
Recovery from a stall
Recovering from a stall essentially requires the pilot to reduce the pitch attitude of the aircraft while simultaneously increasing engine power (or, in the case of a full power stall, doing nothing to engine power). Also, the pilot should ensure that the wings are brought level with coordinated rudder control to prevent one wing stalling, thereby forcing the aircraft into a spin.
Once the aircraft starts gaining airspeed, the pilot needs to gradually pull back on the control column until the aircraft demonstrates a positive rate of climb. Pulling back too quickly on the control column could result in a secondary stall.
As I mentioned in my earlier post, I’m going to start by giving you, the reader, details of flight training as I go along. I know I promised a day-by-day commentary, but that (a) gets to be too verbose and, (b) does not change that much on a day-by-day basis.
Most flight schools seem to start their trainees off real slow, by having the student go through things like climbs, descents, shallow turns, straight and level flight, etc. before getting into things like slow flight, stalls and steep turns. However, the folks at DuBois Aviation seem to take a contrarian view preferring, instead, to have the student start with these difficult manoeuvres so that the student has more time to work on it. Also, as my instructor mentioned, an understanding of the power-flight attitude couple and its impact on flight is essential to an understanding of landing. And we all know that we do want to land at some point of time!
Let us get into each of these manoeuvres in detail now.
The whole idea of training someone in slow flight is to help them develop a feel for the aircraft’s controls at very slow airspeeds, such as those during a landing. For the purposes of training, this manoeuvre is conducted at a speed just over the stall speed of the aircraft. Here’s roughly how it’s done:
- First do a clearing turn (a combination of two 90 degree turns, one in each direction, or a 180 degree turn, to ensure that there is no traffic around you while you attempt this manoeuvre.
- Next start reducing the aircraft’s speed by reducing the throttle. Hold the altitude steady by increasing the aircraft’s pitch attitude.
- When the airspeed falls below the maximum flap extension speed, start extending the flaps, in increments until you have extended full flaps.
- Once the aircraft is stabilised, perform climbs, descents and shallow turns. Each of these manoeuvres requires a coordinated increase of power and aircraft pitch to hold the airspeed constant.
Obviously, the one thing not mentioned above is that you trim the aircraft after every change.
So, how did I do on this aspect of my training? As you probably guessed, not too good on my first 2 days. However, towards the end of day 3, my instructor said I was getting the hang of it, and that I was able to mentally correlate the variables (pitch and power) correctly.
Steep turns are manoeuvres that are conducted by rolling the aircraft into a bank angle of 45 degrees (or within 5 degrees of that angle). When the aircraft is in a steep turn, the load factor on the aircraft increases greatly, subjecting the aircraft and its occupants to about 2G. Also, it requires excellent coordination between aileron, elevator and throttle to keep the aircraft at the same altitude and maintain the same bank angle while spinning around in a tight circle.
During your check ride, you are expected to roll into a 45 degree bank and hold the aircraft to within 5 degrees of that bank, while maintaining altitude to within 100 feet of the entry altitude and roll out at a heading that is within 10 degrees of the entry heading. It is tough, and I obviously need significantly more practice to get this manoeuvre correct. However, as my instructor points out, right now I have a grand total of 3.3 hours of total flight time in my log book. It’s not a lot!
During my next post, I’ll talk more about stalls and other manoeuvres.
My first real day of flying was on Sunday, October 16, 2011. A typical southern california fall day – sunny and warm (actually, hot!) with temperatures in the 80s. Ahhh. I do love SoCal when it comes to the weather – earthquakes… not so much. But I digress…
The aircraft I’m going to be flying is the Piper Cherokee PA-28-140. It’s one of the workhorses of general aviation training (along with the Cessna 172). Here’s a picture of the aircraft.
And, here’s a picture of its cockpit.
So, I headed over to my training facility, DuBois Aviation in Chino, CA where my instructor was waiting for me. We spent about 20 minutes in “ground school” going over the previous week’s homework, and then it was flight time.
The first step to flying is to complete a pre-flight inspection (often, just called a “preflight”). My instructor had shown it to me earlier and so, had me do this preflight on my own. I will post more details on the preflight in another post, but for now, suffice it to say that I spent the better part of 15 minutes going the aircraft to ensure that it was fit to fly.
Once preflight was completed, my instructor and I hopped into the aircraft. He talked me through the engine start checklist and I started the engines. I was finally getting ready to fly a real aircraft! Yay!
We taxied out of the hangar towards the runway. Of course, in order to get to the runway, we had to do a bunch of things…
- First we obtained the weather report for the airfield from the Chino ATIS (Automatic Terminal Information Service) on frequency 125.85. This provided us with the weather information as well as which runways are in use, NOTAMs, etc. The ATIS is updated every hour and is always suffixed with a phonetic letter (alpha, bravo, charlie, etc.). The counter resets to alpha after 12 hours where there’s no update or when the date changes. In our case, Chino ATIS was on Juliet (the letter “J”).
- After that, we tuned the radio to frequency 121.60 to contact Chino Ground Tower. This is the control tower that can provide us with taxi clearance to make it to the runway. The communication to Chino ground sounded something like this. Text in red is what we transmitted and text in blue is what we received. I’ll explain more about the communication and what it means in another post.
- Chino Ground. Cherokee Four One Three Two Juliet. Waiting at DuBois Aviation. Requesting Taxi Clearance. Runway Two Six Right. With information Juliet.
- Cherokee Four One Three Two Juliet. Proceed to Runway Two Six Right via Delta.
- Proceed to Runway Two Six Right via Delta. Cherokee Four One Three Two Juliet.
- We then proceeded to the pre-takeoff area at Runway 26R via taxiway D for our pre-takeoff engine run up.
- Once the pre-takeoff checklist was completed, we asked Chino Tower for permission to take off. On receiving permission to take off, my instructor asked me to do it! Cool!
- Takeoff is pretty simple to do – it’s the landings that are hard! I rolled the aircraft onto the runway, aligned it with the centre line of the runway, advanced the throttle to full power and off we went down the runway. All single engine aircraft exhibit a left turning tendency at high speeds and high angles of attack. So, a little bit of right rudder kept the aircraft nice and lined up with the centre line.
- When the airspeed indicator showed about 60 knots, I began to pull the control column towards me and the aircraft started “rotating”. After establishing an airspeed of about 80 knots, I let the climb continue until we reached an altitude of about 1500 feet.
Now that we were airborne, the fun really began.
Unfortunately, I’m out of time now. More on that later…
Looks like someone must have noticed my whining about the TSA approval because I received it a few minutes ago!
Next Steps… Start flight lessons!
After the tragic events of 9/11, the US government decided that any non-US Citizen (i.e. an alien) would require TSA clearance to start flight school in the USA. The TSA clearance adds a bunch of expensive hoops for all non-US Citizens (like me) who want to learn flying in the USA.
Here’s what you need to do to qualify:
- First start a candidate application at https://www.flightschoolcandidates.gov/
- Upload scanned copies of your passport (required), US driver’s licence (required) and green card or visa (as applicable to your immigration status).
- Finalise the flight school that you’re going to attend.
- Start a new training request with the name of the flight school that you’re going to attend. This results in the web site sending an email to the flight school.
- Once the flight school approves, the TSA checks the uploaded documentation and, if it is acceptable to them, sends you a request to pay the processing fee (which is currently $130).
- Once the fee is paid (it can only be paid online) the TSA will send you fingerprinting instructions.
- On receipt of the fingerprinting instructions, work with an authorised fingerprinting provider in your area to get the fingerprints and have them send it to the TSA. The fingerprints typically cost about $99.
- On approval of the fingerprints, the TSA will send out an email to your flight school approving your candidature and allowing you to start your flight training. It is illegal for the flight school to commence your flight training until the TSA approval is received by them.
So, here’s the kicker… the fingerprints normally take any where between 10 days to 30 days to get approved. I got my fingerprinting done on Tuesday, September 28th. Now, I have to wait until my approval comes through. Hopefully, it’s some time this week so I can actually get started this coming weekend on my training.
As one of my colleagues put it, this is like a child waiting for Christmas to open all those delectable gifts that are under the Christmas tree!