Flight Training Advice And Analysis
In this video, I demonstrate why the VASI is not appropriate for VFR flight to the runway and a steeper approach should be used when possible. Continue reading “Is the VASI glidepath high enough for a safe VFR approach?”
To enter class C or D airspace you only need to establish two-way radio communications. You will also need two-way communications to enter class A or B airspace, along with some other requirements. Continue reading “Establishing Two-Way Radio Communications”
My local flight school had an unexpected incident recently involving a failure of the nosewheel. The plane was a Piper Arrow, which has a landing gear system that fails to the down and locked position. This means that if you lose hydraulic pressure, the gear will fall down and lock in position. It has an emergency extension system and even an automatic extension system if you forget.
The Piper Arrow is part of the Cherokee line of Piper aircraft. Over 32,000 of these popular planes have been built since 1961. The arrow itself is a very common plane and you might expect all of the problems to be ironed out. But this is aviation, and anything can happen, which is why we train so hard for what might happen.
In this case, the aircraft departed on a training flight with a very experienced student and a very experienced instructor. I know both of these people personally and have flown with them. They are some of the most qualified people anywhere to handle an emergency like this.
The flight called for some stall practice, which involves flight in landing configuration, so the gear was lowered and raised several times.
However, the final time that the gear was raised there was a problem, although the pilots didn’t know it yet.
Upon returning to the traffic pattern the landing gear lever was lowered and the two main gear lights illuminated. The nose gear light did not illuminate! So they departed the pattern and tried raising and lowering the gear to no avail. They contacted the flight school and flew past so others could take a look.
The nosewheel was down, but not quite all the way, and it was off to the side a bit.
Luckily they had a good amount of fuel so there was time to think about how to handle this situation. The biggest question is about whether to land with the main wheels down or up.
A main wheels down landing would damage the nose of the aircraft if the gear collapsed, and the prospect of sliding in nose first was not very appealing.
However, landing with the gear up guaranteed damage to the plane and danger to the pilots even if the nosewheel was planning on staying extended. In addition, if the nosewheel did stay extended the landing would be very rough as the aircraft would necessarily roll to one side of the nosewheel.
They chose to land with the main wheels extended and locked.
The landing was beautifully executed! The instructor touched down gently on the mains and kept the nose off the ground as the aircraft slowed. They pulled the mixture out so the engine would shut down just as the prop touched the ground.
The nosewheel slid partially up into the wheel well and the prop touched down with a loud metallic scraping noise. The plane settled onto the nose and slid down the runway. It appears that the brakes were not applied and the plane slowed down to a stop after a few hundred feet.
Some other instructors ran to the plane as the firetrucks rolled up behind them. There was no fire, and the damage to the plane was surprisingly minimal. The propeller is bent and the whole engine will need to be inspected and likely replaced, along with the motor mounts. The removable cowling is toast and the nose gear systems need to be rebuilt, but that is a very gentle outcome for the type of failure experienced.
This whole problem was caused by a small piece of metal that guides the nosewheel to a centered position as the gear is retracted. This guide ensures that if the wheel is down but turned slightly, it will be lined up to fit in the wheel well.
When the gear was raised after the last stall practice, the guide bent on one side and the roller that normally travels down the middle of the guide fell off to that side. Worse still, the bend in the guide rail was very sharp and it acted as a hook, grabbing the roller as the gear was extended! In the image below I am holding the bent guide. See the left side, which is how it is supposed to look, and the right side which has bent down into a hook!
IMPORTANT: Please read my disclaimer below about accident studies
This study and all accident studies are not meant to judge anyone, their actions, or their skills as a pilot. I do not claim to know what the pilot did or what he/she was thinking. The purpose of these accident studies is to better understand what causes accidents and how to avoid them. Comments and other points of view are always welcome as long as they are respectful towards everyone involved.
Retractable gear planes fly faster and save fuel because they have less drag. The downside is that there is a risk of landing with the wheels retracted and causing significant damage to the plane. For this reason, some planes have been equipped with an automatic landing gear extension system.
There is a fairly common illusion that can make landing more difficult at unfamiliar airports, especially at night. The illusion occurs because we tend to get used to a certain runway width.
When approaching a runway that is narrower than you are used to, you may feel like you are higher than you really are.
This happens as a simple matter of perspective. Your brain uses the size of common objects to interpret your distance to them. However, runways are not common because every is a little bit different. Your brain sees the narrow runway and thinks it is a runway of normal width, only farther away.
Of course, this can be very dangerous as you may contact the runway unexpectedly while you believe you still have some distance to descend. You may land in a flat or even nose down attitude. I have seen students suffer from this illusion many times. Typically, they realize it about one second before touchdown, when I grab the yoke and pull until the plane is in the correct landing attitude.
The illusion also works the other way too. If you are approaching a wider than usual runway it will appear to be closer than it really is. This is not as dangerous as a narrow runway, but still worth avoiding.
As I said above this illusion is far more common at night when it is difficult to see and the runway lights provide most of the information about your height.
There are several parts to avoiding this illusion.
IMPORTANT: READ MY DISCLAIMER AT THE END
The landing gear is an amazing system built to take the stress of landing and handle side loads while turning. A retractable landing gear is even more amazing because it also has the ability to fold up into the plane and reduce drag.
The landing gear is controlled with a simple up and down handle. But what happens if you put the handle in the up position while parked on the ground? Continue reading “The Landing Gear can’t be Retracted on the Ground”
Flaps are very useful for giving an airplane good handling characteristics at low speed. They are vitally important for giving fast planes the ability to go slow for takeoff and landing.
There are 6 types of flaps
A simple hinge at the rear of the wing is used to make plain flaps. They are easy to design but they can’t provide much lift before the drag increases very significantly.
Since increasing drag is one of the purposes of a flap the performance is not too bad for landing. When taking off though, drag is not desired.
The reason this flap has so much drag is because the air from above the wing tends to separate and become turbulent when it has to flow downwards at such a steep angle. Think of it like a car on the highway having to make a sharp turn to stay on the road. This airflow separation is like that car spinning out because it can’t make the turn.
Turbulent airflow separation above the wing reduces lift.
The split flap surface is actually below the wing and pushes down out of the bottom. It does provide some lift but it creates a lot of drag and is almost like a speed brake under the wing.
This is the most common type of flap because it is relatively simple to design and build but provides a huge benefit over the plain flap. The slot created when the flap extends allows air to flow from under the wing.
This airflow provides a cushion for the air from on top of the wing to keep it from separating. It also flows along the top of the flap surface. These two benefits combine to create a lot of extra lift.
Fowler flaps are complex but provide a lot of benefit. They act like slotted flaps opening up a channel for air, but they also slide outwards as depicted below. By sliding out from the wing they greatly increase wing area.
Put simply, they make the wing bigger. A bigger wing means lots of lift!
Most modern airliners use double or triple slotted fowler flaps. These have several flap surfaces that extend out from each other as the flaps are lowered creating a much larger wing with several slots for air to pass through.
This modification to the leading edge of the wing provides a channel of air that is pushed up over the wing and channeled towards the upper surface. At low speeds, this simple fixed device can increase the critical angle of attack (the angle at which the wing stalls). This means that the plane can fly much slower without stalling.
Slats are another type of leading edge flap. They slide down at low speeds and provide a large increase in lift like the fixed slot. The benefit of the slat is that it is retractable and won’t create extra drag at high speeds because it slides up into the wing surface.
I have been watching this particular accident for more information since the day I first saw it in the news. In short, a helicopter was giving a routine tour of New York City when it was forced to make an emergency landing in the Hudson river. The pilot survived but all 5 passengers drowned.
Liberty Helicopters gives tours of New York with the doors removed and passengers riding in harnesses that keep them tethered to the helicopter. This allows them to freely take photographs without falling out. These harnesses played a critical role in the accident.
The problems began when a passenger’s tether(some sources report that it was passenger’s bag) slipped beneath the fuel shutoff lever and pulled on it. The pilot began seeking a place to land as the engine died and did not realize that the shutoff had been pulled.
He considered landing in central park but decided there would be too many people around. Instead, he made his way to the river and inflated the floats designed to allow the helicopter to land on the water.
As he prepared for the landing he realized that the fuel shutoff had been activated and began a restart. The timing was wrong though and the engine would not restart fast enough. He followed the procedure and shut the fuel off again just before impact.
I say “impact” because you can see in the videos of the crash that the helicopter did not land gently at all. This could be because of a poor autorotation, or just because there was not enough energy available to begin with.
After landing the helicopter began rolling to the right and was quickly upside down. This is one of the parts that upset me the most because these floats are designed to keep this from happening. However, a malfunction caused the right side floats to not inflate properly!
As it hung under water the skids were the only thing visible. The pilot was unable to free anybody else and he was picked up by a boat responding to the emergency. A big part of this tragedy was the harness system that held the passengers trapped underwater. The tour company supposedly instructed passengers that they were to use a knife attached to the harness to cut themselves free in an emergency. This obviously was not realistic as nobody was able to do it, including a firefighter who was among those lost.
An accident like this produces more questions than answers because there are so many things that went wrong, and if just one of them had gone right these people would still be alive today.
There are a number of things that could have changed the outcome. In this case, the biggest part of the accident chain was built into the company’s operation with the tethered harnesses. But if the floats had functioned this would not even be considered.
It is important to reflect on these accidents even if it may be difficult to stomach. As pilots, we have a grave responsibility for the safety of others. This is why everything must be done with seriousness and absolute professionalism.
I pray for all those involved in this terrible tragedy.
IMPORTANT: Please read my disclaimer below about accident studies
This study and all accident studies are not meant to judge anyone, their actions, or their skills as a pilot. I do not claim to know what the pilot did or what he/she was thinking. The purpose of these accident studies is to better understand what causes accidents and how to avoid them. Comments and other points of view are always welcome as long as they are respectful towards everyone involved.
We commonly think about how the wind pushes the airplane, but did you know that the wind pulls as well?
Cruising with a tailwind pushes us forward while headwind pushes us back. If we are flying with a crab angle we can look at the ground and get the feeling that we are flying sideways. In these cases, the wind is pushing us from whichever direction it is coming from.
The previous posts about traffic patterns have assumed that you are operating at a non-towered field. This is because at a non-towered field, you are the controller along with any other pilots in the pattern. This post will deal with the pattern but leave the bulk of the details about towered communications out. Look for towered communication details in another post.
Towered operations follow the same pattern concepts with some exceptions. The biggest difference at a towered field is obviously communication. You don’t announce your position as you fly around the pattern. Instead, you make contact with the tower and they will give you directions to fly.
You will rarely fly a complete pattern at a towered field and rarely use the 45. Instead, the controller will decide where you will enter the pattern.
For example, if you are approaching Lancaster, PA (KLNS) on a heading of 090 to the airport and runway 8 is active you will likely be told to maneuver for the straight-in for runway 8. This does NOT mean that you should fly around the class D airspace and enter on a 45 for downwind runway 8. It DOES mean that you should turn to the right and line up on a long final for runway 8 (no downwind or base leg at all).
If you are coming from the opposite side of the field you will likely be asked to enter left (or right) downwind. Again, you will not fly a 45. The only way you would fly a 45 is if you happened to be coming from a direction where the 45 would be. But in this case it is not called a 45, you will just be asked to enter downwind.
Remember that the purpose of the complete pattern at a non-towered field is to help pilots control the airspace by flying in expected ways. At a towered field the controller is handling this and will give you instructions to get you to the runway relativley quickly.
As I will say again and again: if you aren’t sure, just ask.
They may also ask you to report a position. For example, they may say “Cessna 12345 report 5 mile final runway 8”. When you are on final 5 miles from the runway you would say “Lancaster Tower, Cessna 12345 5 mile final runway 8”.
From there the controller will usually clear you to land.
Note that when the controller tells you to report, he is also telling you to enter. So in the example above you are expected to maneuver to final. You are NOT expected to fly around the field and get on a downwind. The only exception would be if you are already on a downwind or base, in which case the controller will usually handle this by saying “Cessna 12345, enter left downwind runway 8, report base turn.” Notice that you have been told how to enter and then how to report.
Another common reporting point is “Cessna 12345, report 3 mile base runway 8”. There are a lot of conflicting opinions about what this actually means.
Some people believe that you should fly a base leg leading to a 3 mile final and report right before you would need to turn final. This seems like the least plausible meaning to me.
Others believe it means that you should fly a long base leg and report when you are 3 miles from turning final. This seems more likely and is what I would actually do in most situations.
Here is the real deal. The controller is not ready to clear you to land so he is telling you to report this point as a way to help him manage the traffic. When you report you are reminding the controller to deal with you. He has chosen a report that hopefully will be a good time to clear you for landing. So as long as you are somewhere in the base leg area and roughly 3 miles from the airport he will be happy. Still, I would love to see an official technical definition from the FAA for this.
The overall point of towered traffic patterns is to go where you are told and listen closely. The controller is managing the flow of traffic and you just need to help him to do his job. If you don’t understand what you need to do, just ask and the controller will be happy to help. Controllers are people like you and me, try not to get intimidated if you are new to flying.
Controllers are professionals, but they can make mistakes, so keep listening and looking for traffic. If the controller tells you to do something that looks unsafe, get clarification. If you are told to do something that you can’t do, say “unable”. It is your responsibility to accept commands given by the controller and turn them down if they aren’t going to work.