Posted on 02/04/2025 1:34:21 PM PST by big bad easter bunny
In this exclusive interview, former airline pilot Jason sits down with John to analyze the recent air disaster at Washington National Airport (DCA). With his years of experience in the cockpit & hundreds of flights into DCA, Jason provides expert insight into what may have gone wrong, the challenge pilots face in high-pressure situations, and what this means for aviation safety moving forward.
Helo too high.
I’ve flown into DCA many times. Landing there is a ridiculously busy scene. I just trusted that everyone knew what they were doing.
Guess I was lucky.
I heard that right before the crash the helo had been told to land.
Would both helicopter pilots be to blame for the altitude? Is this an issue that air traffic control should have noticed?
Obviously someone did not maintain correct vertical separation. The working hypothesis is that someone, possibly the Helicopter pilot, did not correctly adjust the pressure altimeter for local barometric pressure. The radar does not and cannot measure altitude. The aircraft’s reply to an interrogation contains altitude information from the altimeter. ADS-B contains the same information.
Obviously someone did not maintain correct vertical separation. The working hypothesis is that someone, possibly the Helicopter pilot, did not correctly adjust the pressure altimeter for local barometric pressure. The radar does not and cannot measure altitude. The aircraft’s reply to an interrogation contains altitude information from the altimeter. ADS-B contains the same information.
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Explain this to a non-pilot.
Radar can give a very accurate measure of altitude.
Radar measures speed, distance, and horizontal and vertical angles.
The altitude of the aircraft is calculated from the distance and vertical angles.
Aircraft altimeters use air pressure, which decline as altitude increases, to measure the aircraft’s altitude. They must be calibrated to the local ground level air pressure to measure the altitude correctly. The local ground level air pressure is the “Highs” and “Lows” you see on weather maps or on your home barometer.
Dont all helos have a Mode C transponders?
Helos don’t fly, the ground is rejecting them.
(Helos don’t fly, the ground is rejecting them.)
Lol
That’s exactly right 👍
10,000 moving parts flying in close formation around a hydraulic leak.
Seems like someone hacked into the copter and guided it using remote control. Three people in the copter and the other two allowed the copter pilot with his/her hand on the control to travel like a missile into the jet over a sustained amount of time?
Helicopters fly by beating the air into submission
As a former ATC, I fail to understand why they would allow another craft anywhere near a final approach path. 200, 500, 1500 agl is asinine in front of an active runway.
I have an opinion on the vfr for the helo but it’s not an educated opinion as I’ve never flown in one.
Friend flies those helos. Says while that low, they use AGL (above ground ground) measuring equipment, not air pressure altimeters. They use radar pointed at the ground. Very accurate.
Radar give a dash line basically. A transponder is what gives identifying information.
I saw a map where the helo’s flight path went across the approach of the airport’s runway. I am not a pilot, but I cannot understand why anyone would want to fly perpendicular to the runway approach that close.
Airport radar do not measure aircraft altitude. Airport surveillance radar interrogate aircraft with a coded pulse train and receive the aircraft’s pressure altimeter reading in reply. There is also a new message called ADS-B that broadcasts an aircraft’s position, including altitude, once per second.
How does the aircraft know its altitude? To maintain vertical separation everyone has to agree on the definition of altitude. Air traffic control is done using pressure altitude. It is the responsibility of the pilot to adjust the aircraft’s altimeter to agree with the known surveyed altitude above “mean sea level” of the runway prior to departure. Every single time. This is the altitude reported in the signal that the aircraft sends to ATC via interrogations, and ADS-B. Helicopters may have laser altimeters to use when flying at low altitude over water. The helicopter may have been flying on laser altimeter altitude above the water, while reporting a misadjusted (or ignored) pressure altimeter value.
I do not have enough facts to judge for certain, but if I had to bet, my money would be on the helicopter pilot skipping the checklist step for adjusting the pressure altimeter, “reasoning” that she didn’t need it because she was going to use the more accurate laser altimeter. Only the laser altimeter gives reads altitude about the surface, regardless of air pressure.
An alternate hypothesis is that the local air pressure was different in Oklahoma when the airliner took off and no adjustment was made for different meteorological circumstances in DC, though less likely.
Please. I worked in MIT/Lincoln Lab Group 42 who virtually invented the modern Air Traffic Control (ATC) system. (I am in Group 33 Advanced Sensors these days.) I also worked on the design, integration and test of the ASR-11 Airport Surveillance Radar (ASR) when I was at Raytheon. Airport Surveillance Radar do not measure altitude. They use fan beams. The only information ATC has about altitude is from transponder replies and ADS-B.
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