Frequently Asked Questions for Landing Procedures
On January 13, 2015 United Airlines Assistant Chief Pilot Jeff Bayless answered questions from ONCC Technical Committee members regarding landing procedures based on the pilot's experience.
Who controls the speed of arriving aircraft?
The control tower determines the speed of the aircraft. Aircraft speed dictates when the flaps come down. The slower the aircraft, the more flaps have to come down in order to protect the airplane from stalling. All of United's pilots are highly trained on the procedure and safety is a priority.
What is the typical speed of arriving aircraft?
Typically aircraft speed is 180 knots five miles out from the airport. Five miles usually is considered the outer marker for the final approach fix. At that point, landing gear and flaps will be down. Anywhere from about 1,500 feet to 1,000 feet of altitude, the aircraft will have flaps down and will be on autopilot on the 3 degree glide slope. There is a GPS tracking in the ILS system which indicates 3 degrees. If the aircraft goes below 3 degrees it becomes unsafe.
What factor does speed play in landing an aircraft?
Speed also affects the lowering of landing gear. If air traffic has a pilot going too fast approaching the outer marker, he or she has to be slowed down in order to be in a stabilized configuration before reaching an altitude of 1,000 feet. If not, the pilot has to go around. Flight Operations Quality Assurance Program tracks all operations. This system monitors all airplanes. The goal is to have a safe flight and safe landing. Safe flight means the 3 degree glide slope that stabilizes the aircraft.
Does air traffic control dictate the speed of the aircraft?
Based on the amount of traffic and if there are a lot of aircraft involved, air traffic control has to spread out the aircraft for safety reasons. For example, a Boeing 777 would require a smaller aircraft to stay about five miles behind that aircraft. Air traffic also takes into consideration departures. Arrivals are maintained in a "highway" taking into account departing aircraft to avoid conflict. The later a pilot lowers the flaps, the more fuel savings for the aircraft.
Does most aircraft noise come from landing gear?
The greatest noise impact comes from the aircraft engine rather than the landing gear.
Does slowing down the aircraft require more power?
Not exactly. The flat flap wing is very efficient at high speed and a round wing is very efficient at low speed. So at the low end of the angle you have to have the flaps out otherwise the wing will stall.
How is landing gear activated based on air speed before 5 miles out?
Most aircraft are typically at 10 knots at five miles out depending on the aircraft in route. This gives the pilot enough time to get off the runway. At six to five miles out is typically when the landing gear is dropped. Weather also is a factor and not a lot of power is being used at the 3 degree glide slope.
Would increasing the glide slope to a 3.5 degree angle change the experience coming into O'Hare?
If you're at a 5 knot tail wind then the 3.5 degree glide slope would make the aircraft unstable. At 3.5 degree the aircraft may not be stable and might exacerbate the problem and cause the pilot to go around because the aircraft is unstable. The pilot is always following the 3 degree glide slope and there is an indicator that tells the pilot that the aircraft is not on the 3 degree glide slope. There are very few rare occasions that the aircraft would go below the glide slope.
Is there a different procedure during the "Fly Quiet" hours?
There is no difference in training for day or night.
Are United pilots trained specifically for the O'Hare Fly Quiet Program?
All United Airline pilots are trained every nine months and noise abatement procedures are generally discussed.
Are the O'Hare Fly Quiet procedures found in the Jeppesen Manuals?
Not necessarily "Fly Quiet", but pilots are following noise abatement procedures. Pilots are not trained for specific airports such as O'Hare's "Fly Quiet" because noise abatement procedures are in place at ALL airports including O'Hare.
Is the 3 degree glide slope a standard procedure at all airports?
Yes unless terrain poses an issue. The 3 degree glide slope is a stable, safe approach. If an aircraft goes steeper and the winds were an issue, the aircraft would have a problem stopping on the runway.
When does a pilot turn on auto pilot?
That depends on the weather. For example, on a foggy day the auto pilot will steer the nose of the plane on the center line. Pilots turn off the auto pilot to taxi off the runway. On a clear day the auto pilot will be off when the aircraft is stabilized and final flaps are activated on the 3 degree glide slope. The pilot always wants to make the landing as smooth as possible. The auto pilot is a bit more mechanical; a pilot that lands without the autopilot has a much smoother landing.
What determines banking the aircraft?
Aircraft will fly straight ahead until 400 feet and then turn according to the heading given by air traffic control unless there are safety reasons or obstacles. It also depends on the runway and which direction the aircraft is headed. Typically air traffic control wants the pilot to turn fairly quickly to get out of the area. That question would be better answered by air traffic control.
Deviating flights from the preferential flight tracks are of concern, is it up to the pilot or is that turn an air traffic control direction?
The air traffic controller tells pilots when to turn. It would depend on the traffic around O'Hare.
What about the effects of cross winds and the decommissioning of the diagonal runways at O'Hare?
An aircraft angles into the wind and as far as the airplane is concerned it's flying straight into the wind. For the ground track that has to be aligned with the runway so it's called a slide slip, but there is a lot of head wind and the power varies. As you get closer to the ground, the aircraft has to be aligned with the runway. The aircraft is controlled and drags the airplane closer to the ground.
Landing typically happens on the east/west runways and rarely on the diagonal runways.