Peter's Flight Log

What is a Practiced Forced Landing?

As a pilot, you need to be prepared for any situation, especially those that involve unexpected engine failures. This is where Practiced Forced Landings (PFLs) come into play. A PFL is an essential skill for pilots, designed to prepare you for the unfortunate event of a real engine failure.

A forced landing occurs when an aircraft must make an emergency landing due to engine failure or other in-flight emergencies that prevent continued flight to a planned destination. Practicing these scenarios ensures that you, as a pilot, can manage such situations with confidence and skill.

Even though engine failures in well-maintained aircraft are rare, responding to such event is not something any pilot should leave to instinct. Training and immediate response based on a predetermined set of actions can be the difference between becoming a statistic or having a great story to tell at BBQs.

Dealing with a forced landing

Here's what a forced landing procedure looks like.

The process of conducting a forced landing involves several critical steps. When an engine fails, the immediate actions that the pilot must perform are:

1. Maintain Control: Fly the aircraft and keep it steady. AVIATE.

2. Airspeed: Establish the best glide speed to maximize your distance and time in the air. For the Cessna 172, that speed is 68 kt.

3. Select a Landing Site: Choose a suitable area for landing, considering factors such as wind direction, surface, and obstacles. The pilot should constantly scan the ground for suitable forced landing spots as part of the flying routine, so when the emergency happens, most of the selection work has already be done.

After a landing site is selected, the pilot must inform the passengers of what is going to happen next. The passenger will likely know that something is not right, given that the engine has stopped working. Here's an example of this briefing:

Forced landing passenger briefing (example)

Attention, everyone. We have experienced an engine failure and need to make an emergency landing. Don't worry. I have already selected a landing site, and be assured I am well trained to do this safely. Please listen carefully and follow these instructions to ensure your safety. Please remain calm and listen to my instructions. Make sure your seatbelt is securely fastened. Pull the strap tight and low across your lap. When I say "Brace, brace, brace," lean forward, placing your head against the seat in front of you or on your knees if possible. Use your arms to protect your head. Remove any sharp objects, like pens, from your pockets, and your glasses unless you need them to see. Unlock and open your door before landing. If you are in the front seat, be ready to open the door upon landing. Once we are on the ground and have come to a complete stop, exit the airplane and move behind it and away from the engine.

Right after the passenger briefing, the pilot should issue a Mayday call. The purpose of this call is to alert air traffic control and nearby aircraft about your situation. Provide your location, nature of the emergency, and intentions. Here is an example of this call:

Mayday call for forced landing (example)

Mayday, Mayday, Mayday. Sydney and all stations. Alpha Hotel Hotel, Alpha Hotel Hotel, Alpha Hotel Hotel. Loss of engine power, conducting a forced landing. Currently 1 mile north of Bringelly, altitude 2,000 feet. Two POB (persons on board). Intending to land in a clear field. Will call from the ground if possible. Mayday, Mayday, Mayday. AHH.

This call provides your aircraft identification, nature of the emergency, your current location, altitude, number of people on board, and your intended action, which helps Air Traffic Control and emergency services respond appropriately.

High Key Low Key

The pilot is now committed to continue with the forced landing. In this flight, Bob demonstrated the High Key Low Key technique. You can see a depiction of this technique below.

The High Key Low Key technique is a structured method used during forced landings to ensure a safe, controlled approach to a chosen landing site when an engine failure occurs. This technique helps pilots manage their altitude and position effectively, allowing for a successful landing even in emergency situations.

The High Key position is the initial reference point in the forced landing pattern. Here's what you need to know about it:

1. Altitude: Typically around 2,000 feet above ground level (AGL), but this can vary depending on the aircraft and the situation.
2. Location: Positioned directly over or slightly offset from the chosen landing site, usually the beginning of the intended landing field.
3. Objective: From this position, you can make a 360-degree turn if necessary to lose altitude while keeping the landing site within view. This gives you options to adjust your approach if needed.

The Low Key position is the next key point in the descent, allowing for further adjustments before final approach:

1. Altitude: Approximately 1,000 feet AGL, about halfway down the intended landing field.
2. Location: Positioned abeam (to the side of) the intended landing site, typically near the midpoint.
3. Objective: This position allows you to begin your final descent and adjust for a stable landing approach.

During the transision from high key to low key, keep the landing site in sight at all times and adjust the descent rate and bank angle to arrive at Low Key at approximately 1,000 feet AGL.

From low key, make a final turn towards the landing site. Of course, continue to manage your glide speed. Adjust the approach path to touch down as close to the intended landing point as possible.

CFM

Right after an engine failure at altitude, the pilot should try to restart the engine. Often the engine has stoped because of a small number of issues. The most important of those are incorrect settings for the carburator (if fitted), fuel, and mix.Here's what we do:

1. Set carburator heat on in case carburator icing is the cause of the engine problem. VHH is fuel injected, so we don't worry about a carburator.
2. Fuel. Check the fuel level indicators (are we out of fuel?). Check the fuel selector (should be on both).Turn on the fuel pump.
3. Mix. Set to rich in case the mix was too lean.

Move the throttle in and out a few times to see if the engine responds. Use the starter, to see if that helps.

It is possible that the engine will restart after the above actions, and then we'll be able to return (or at least have the option) to return to the airport.

Judging glide range

In a Cessna 172 or other high-wing aircraft, judging the glide range once you have established the best glide speed involves a combination of visual cues, understanding the aircraft's performance characteristics, and using landmarks or reference points.

For a Cessna 172, the best glide speed is typically around 68 knots. This speed provides the maximum distance for the altitude lost. The Cessna 172 has a glide ratio of approximately 9:1, meaning it can glide 9 feet forward for every 1 foot of altitude lost under ideal conditions.

When using the high key low key technique, the pilot can use the wing struts as a visual aid to determine glide range. On the left side (pilot's side) looking out the left window, any field that is below half way down the strut can be considered within range in nil wind conditions. If looking out the right window, that marker on the strut will be a bit higher.

Another technique (especially useful if there is no strut, such as in a low-wing airplane) is to use your arm. Imagine your arm, raised at around 10° from the horizontal. Anything below the arm can be consired within range in nil wind.

A tail wind will increase the glide range, and a head wind will decrease it.

Selecting a suitable field. 

A mnemonic check for selecting a suitable landing field is WOSSSSS.

• W: Wind (prefered into the wind approach).
• O: Obstacles (avoid trees, rocks, power lines).
• S: Size and Shape, in relation to wind.
• S: Surface and Slope
• S: Shoots, undershoot or overshoot areas.
• S: Sun, position relative to final approach.
• S: Civilization or Services, i.e. proximity to help.
  

FMCOST checks

We have already done the basic CFM checklist, but on downwind we'll do another attempt to restart the engine followin the FMCOST checklist.

• F: Fuel on and contents checked. Change tanks. Boost pump. Primer locked.
• M: Mixture set to rich.
• C: Carburator set to hot.
• O: Oil check pressure and temperature. 
• S: Switches, check magnetos on both.
• T: Throttle, cycle in/out a few times.
  

If none of these actions restart the engine, the pilot is commited to the first landing.

Did I actually land in a field in this practice?

Therefore, PFLs do not include an actual landing. The minimum altitude is 800 ft MASL, after which we set full power and climb to practice altitude at 2500 ft.

Defrief