Porpoising aircraft is not bouncing. Instead, it occurs if a pilot fails to control the plane after the first bounce. I explained in this post how a pilot can prevent a porpoising aircraft and why it happens.
Unable to prevent a porpoise on landing can lead to a disaster.
Thus, it would be best if you learned everything about porpoising aircraft on landing:
- What is a porpoising plane?
- What causes an airplane to porpoise?;
- What to do if you enter a porpoising landing?;
- Best practice to prevent aircraft porpoising;
- Dangers of porpoising on landing.
Imagine you are a private pilot on a cross-country flight. You are about to flare, and a sudden gust of air pushed your aircraft to continuous oscillation of bounces over the runway. What will you do?
What is a porpoising aircraft?
Imagine an aircraft bounces off the ground, and you push hard to land the airplane, which may cause repeated bounce of the plane. The plane’s repeating bounce will continue a cycle over the runway until the pilot nose dive and crash land the airplane.
This continuous oscillation looks similar to a porpoise jumping on the surface of the water.
Porpoising aircraft is a situation that follows if the pilot fails to control an airplane bounce correctly.
Hence it is crucial to know the reason behind a porpoise on landing.
What causes an airplane to porpoise?
To understand a porpoise on landing, we must first understand what causes an airplane to bounce on landing.
Typically newbie pilots bounce in landing. The reason for inexperienced pilots to bounce on landing is because:
- Either they sink too fast over the runway;
- Or the approach speed of the plane was higher than recommended;
- Not rimming the airplane properly;
- Another reason for a bounce can also be the aircraft’s weight.
Like I mentioned, a bounced landing is likely to make aircraft porpoise.
Assuming you as a pilot approached the runway with a higher airspeed than recommended. Now when you flare with a high airspeed, it is likely the aircraft will float.
When the aircraft floats, the plane loses airspeed quickly and sinks faster, resulting in a bounce.
Naturally, after a bounce, the pilot’s instinct is to push the aircraft yoke for a touchdown.
In this situation, pushing the airplane yoke too hard is a mistake.
If the airplane touches the ground with nose landing gear first and main landing gear later at a high airspeed, the inertia at the rear of the aircraft will make the structure bounce off the ground again.
I believe the main reason for a porpoising aircraft is high approach airspeed.
The repeating bounces will ultimately go out of the pilot’s control and crash land the aircraft.
In another instance, while you were about to touchdown, you touch the ground with nose landing gear first.
This situation can also lead to a porpoise from the first bounce. Once the nose landing gear touches the ground first, the inertia on the tail of the aircraft pushes the aircraft off the ground and gains altitude. Gaining a very high altitude at this stage also can be the beginning of a porpoising landing.
What to do if you enter a porpoising landing?
The best thing to do when you enter a porpoising landing is to go around. It’s as simple as that.
An aircraft porpoises after a bounce. Once a pilot thinks he can’t control the aircraft anymore after the second bounce, it is best to go around.
After the first bounce, if the airspeed is too slow, the aircraft will touch the ground, but the touchdown impact will be immense.
If the aircraft did not stop the second time, instead it gained more altitude after the second bounce, the only thing you should do is go around. Pilots unaware of the porpoising situation might try to force the aircraft.
If you have gained altitude after the second bounce, immediately add full power and go around.
On the second approach, ensure your approach airspeed is correct, and your sink rate is between 500 to 600 feet per minute on final.
Trying to stop a porpoise on landing will make the situation worse. It is better to save yourself and the aircraft and attempt for a landing again.
Best practice to prevent aircraft porpoising.
To prevent an airplane from porpoising, you have to master controlling the airplane speed.
Practice slow flights and maintaining airspeed.
Also, learn to trim your aircraft from an early stage of your flight training. Many student pilots avoid trimming plane.
Finally, practice practice and practice landing touch and go.
No pilot can claim that they never had a bounced landing. It’s common for all pilots.
However, a porpoising aircraft is a situation that follows uncontrolled bounces.
An untrained pilot will fail to control a bounce correctly and enter a porpoise.
To prevent porpoises on landing, a pilot must maintain airspeed from the beginning of the landing phase.
VFR pilots have a set of rules to follow and airspeed to maintain from the time they enter downwind. The airspeed is variable for different aircraft, but the technique is always the same.
The pilot must maintain airspeed on all legs of the approach.
Failure to maintain recommended speed on the final can be critical.
Typically the approach speed on final is 1.3x VSO of the aircraft you are flying.
Maintain this airspeed together with a descend rate of 500/600 feet per minute.
Once you are over the runway, you can break the glide and allow the airplane to sink slowly.
Another problem among student pilots is to flare too early. Remember to pull the yoke gently and not abruptly.
Pilots tend to pull the yoke abruptly if they did not trim the aircraft properly.
The reason for aircraft floating is abrupt back pressure on the yoke resulting in lift and aircraft gain altitude.
Other reasons for an airplane to float are the ground effect or a sudden gust of air that generates lift over the wings.
Therefore even you performed flawlessly, the ground effect can result in the airplane bouncing.
The best practice to recover from a floating is by adding a little bit of power and not allowing the airplane to sink fast. A high sink rate, even at 10 feet, will cause a harsh impact.
With that hard impact on the ground, your aircraft landing gears will bounce.
Prevention of a porpoising aircraft begins from the downwind leg and how you react after your plane’s first bounce.
IF you think the aircraft is going for a second bounce, don’t allow it have a nosedive. Instead, go around for a second attempt on landing.
Dangers of porpoising on landing.
Porpoising on landing and failure to recovery will induce the airplane to nose dive. A nosedive at high airspeed indicates a severe impact on the ground, breaking the landing gears and propeller leaving the pilots and passengers injured.
As a pilot, don’t wait until you enter a porpoise landing or never try too hard to bring the airplane to the ground. If the situation comes to that, the only thing you can do is to go around.