The National Transportation Safety Board (NTSB) Investigative Update for February 4 reports that most recent information shows the Army Black Hawk helicopter altitude displayed in the control tower showed 300 feet at the moment of impact. However, that readout is rounded to the nearest 100 feet, the NTSB said, suggesting the helicopter altitude could have been as low as 251 feet, per that data.
Well the radar data said the CRJ was at 325 feet plus or minus 25. Then to say something ridiculous like the Helicopter could have been as low as 251 feet…they had a direct hit. So if they were separated by even 75 feet they would have missed. So let’s not play with numbers game trying to excuse blame. Whoever thought that this corridor was a good idea is ultimately to blame. Remove the corridor today.
I agree with removal of the corridor. Even more, if security is that critical in DCA airspace then DCA should be shut down permanently. DCA is not that important (although Congress may think otherwise) to risk having another accident with the resulting loss of life with security measures that reduce safety of airliners. Dulles can easily handle the increased air traffic. Imagine the outcry if a general aviation airplane had been involved!
I am old enough to remember that until the mid 1970s helicopters could not fly at night because pilots had to be able to see the horizon.
Night vision goggles (early ones guaranteed headaches) and fancy instruments changed that – a bit.
But it still is a dangerous thing to do.
Now we learn that one of the most advanced military helicopters appears on radar screens with approximate altitudes rounded out to 100 feet? Presumably that means the instruments in the control panel are also “rounded out.”
I know most helicopters have windows in the floor to help land, but it seems things are going back to the 1970s again.
Maybe now military aircraft will be required to have ADS-B turned on at all times with the SFRA/FRZ. They can have it off at their discretion.
They do operate with their Mode S transponders on all the time.
I fly that airspace, and you rarely see military aircraft on your screen. We always rely on ATC traffic calls for them
I believe you are misinterpreting what was written. All ATC radar screens round the reported aircraft altitudes to the nearest 100 feet, independent of what the instruments in the aircraft are displaying to the crew.
I believe what they mean is that the reported altittude of the CRJ was “325’ +/- 25’” and the reported altitude of the Blackhawk “could have been as low as 251’”. Obviously at the point of collision their actual altitudes converged. The question then is, were they both reporting nearly the same altitude at that point, and if not, were they still within the legally-allowed tolerances.
The circling approach to runway 33 is not the issue. A better long term solution would be “Route one NA during runway 33 operations.” Busy air carrier airports cater to fixed wing arrivals and departures. Not politicians or training. Every airport I worked. If you were busy, helicopters were told “remain clear of bravo airspace.”
The CRJ had ADSB, so the data (being the aggregate of several Potomac TRACON radar sources and ADSB) is going to be more accurate than only the radar sources for the Blackhawk which didn’t have ADSB. Obviously they hit. And obviously lessons will be learned from this. The point is to figure out why they hit. This accident could very well be the impetus for requiring all military aircraft to have ADSB while flying in non-military controlled airspace (which, in my opinion, is long over due).
150-200’ of separation on short final is a near miss in any book. And that was designed into the system. Altimeters are considered acceptable for IFR if they are accurate to within 75’. If we give the raw data of every flight for a month through that airspace to a statistician and they could generate the odds of two aircraft passing the same place in space at the same time. Assuming everyone does everything correctly, I would bet the odds are NOT zero. Also, visual separation is probably much more reliable in the daylight hours in a tight corridor like that DCA airspace.
Just so everyone knows, FAR 43 appendix E is where the standards are for FAR 91.411 testing of altimeters and reporting.
At these altitudes the allowable error for the altimeter indication is + - 20 ft. This is whether it is a pneumatic gauge or air data computer derived.
The standard for altitude reporting in any format, Mode C or Mode S is + - 125 ft. from the altimeter indication at any altitude.
Just offered up for reference.
OMIGOD, YES!!! BRILLIANT!!! SHUT IT DOWN PERMANENTLY!!! As tragic as this was, an airport that handled 25.4 million flights (says Wiki) in 2023 should be shut down permanently, because it isn’t important. BTW, I’d like to see something factual about your claim that security measures jeapardize safety.
OMIGOD, YES!!! BRILLIANT!!! SHUT IT DOWN PERMANENTLY!!! As tragic as this was, an airport that handled 25.4 million flights (says Wiki) in 2023 should be shut down permanently, because it isn’t important. BTW, I’d like to see something factual about your claim that security measures jeapardize safety.
The fact that the helicopter was where it was is enough, along with the helicopter route they were flying. The secret service has wanted to close DCA for years and would do so if Congress would allow it. Dulles has been under utilized ever since it was built, mainly because Congress persons are too lazy to drive all the way to Dulles from downtown DC to catch flights. General aviation has been banned from using DCA (except for severe restrictions).
Yes, but judging distance at night with bright landing lights can be deceiving. Sometimes a plane can be several miles away and facing you so that it appears to be much closer. I think the opposite can also be true…being much closer than you think.
I just think it is crazy to sanction crossing under an aircraft on final approach such as happened by design at DCA. It borders on formation flying, but crossing or head on.
This was an accident waiting to happen. The holes in the swiss cheese finally lined up. The fact that there were near misses reported in the past and nothing was done to prevent this accident is unbelievable.
There are actually FOUR different sources / types of altitude displayed, transmitted or visible in the respecitive cockpits plus the FAA radar decoding of same. Now add that the Kollsman window altimeter settings could be set differently, too … adding some correlation / actual altitude discrepancies.
First off, altitude ON the airplane is generated either by a “blind” encoder (separate from the altimeter) or by a combination altimeter / encoder. MOST GA aircraft use a separate unit. So there could be a correlation issue between what the blind encoder is transmitting (or being data recorded) and the actual altimeter reading the pilot sees. FAA Regs require that correlation to be within 125’. In view of what happened and the requirements for holding a 200’ altitude, this large correlation error number seems ridiculous; It would be possibe for the helicopter pilot to SEE 200’ yet be at 325’. Same thing for the CRJ in reverse.
Further, there are two types of blind encoders; I have no knowledge of the systems in either airplane. Older discrete parallel wire encoders were only accurate at 100’ increments. Newer serial altitude encoders are accurate to either 25’ or 10’ … I can’t remember. Maybe Larry Anglisano can shed light on this. My point it, the encoders themselves may not have been reporting that accurately to FAA radars.
I do not know what type of altitude encoding equipment was aboard the helicopter but – think of it – the helicopter pilot may have been seeing 200’ when the helicopter may have actually been at 325’. Assuming the CRJ was at the correct RNAV approach altitude and on the 3 deg. VASI path (SO far, that seems to be the case), then this small allowable altitude error could be where the problem was.
Allowing ANY helicopter ops on that approved ground path at night when runway 33 is in use at DCA was the beginning of the accident chain IMHO.