February 4
Is there a data record of what was displayed on the ATC monitor? Or are they just saying 200 ft is what the tower remembered seeing? Big difference. Also, the crash happened rather close to the runway threshold, but heli Route 4 hugs the eastern river shore. Whatever it’s altitude, the Blackhawk was out of position.
1 reply
February 4
A minor nitpick, but a helicopter is not a “plane”, though it is an “aircraft”.
3 replies
February 4
▶ gmbfly98
Isn’t it saying that the CRJ’s data says it was at ~325 at time of collision, so the helicopter’s reported 200 is a discrepancy?
2 replies
February 4
▶ rick.freeman100
Yes. The radar data and audio is recorded, much flight a FDR/CVR, and analyzed.
February 4
▶ CallMeDave
That’s my understanding as well
February 4
▶ CallMeDave
The NTSB briefing was really tortured, with one briefer taking long swigs from his water bottle more than four times while facing the camera. At one point, it was said that there is up to a five second delay between altitude reporting from Blackhawk and display of that altitude on the controller’s screen, but the controller did see 200’ reported (he didn’t say “at the time of collision”). They seem to be going to extraordinary lengths to not blame the Blackhawk.
Separately and not officially, there are credible reports that the Blackhawk pilot had not flown in two years and was getting re-certified for the helo and the mission. The pilot had been working in the White House for the past two years and was relieved of that duty on January 20.
2 replies
February 4
The article said “…discrepancy between the radar data and the FDR and ADS-B gear on the CRJ700 that was also involved from the FDR.” Wha??? I have higher expectations of technical authors than this word salad. Do better.
1 reply
February 4
▶ gmbfly98
He may have been referring to the RJ and not the helicopter.
February 4
Why aren’t civilian and military FDRs recording the same streams of data? No timestamp from the chopper FDR?
February 4
▶ lynn.jones
The delay is a product of the rotation speed of ASR. ASR rotates at roughly 12.5 RPM, in order to provide target and data updates in a timely manner but still be able to have the range required for accurate target tracking out to the limits of the airspace under facility control. The radar antenna only receives that information when it is pointed at each target and the information is immediately transmitted back. Thus there can be up to an approximately 5 second delay in actual location and altitude information received by the ASR, processed by the host computer, then sent to the controllers’ displays. Controllers working radar are aware of that delay. Newer systems use information from multiple radar sites and will update once per second. I can’t speculate on what system DCA uses but I would think they use the new, fused system.
1 reply
February 4
A data delay might be why the FAA doesn’t show 300’+ , but ADsS-b Exchange showed the heli climbing from 200’ prior to the collision. The FAA is broken and IF there was a delay in the data, thats part of what has to be fixed at the FAA.
1 reply
February 4
▶ lynn.jones
This article on the Blackhawk pilot was published two days ago, and provides insight into the person she was. I’m sure it won’t change any of the wild speculation about whose “fault” it was, but there were other victims of this tragedy besides ice-skaters.
February 4
▶ RtrdCtrl
Even once per second may be too slow.
February 4
As a former airline pilot, I believe this collision begins with whomever approved a helicopter corridor through the short, short finals of airplanes approaching from the south into DCA. To me, the altitudes are a moot point because anywhere on the river is not safe.
Using a standard 3-degree glide path of approximately 300’ per mile, starting at 1,500’ at 5 miles out, would put the CRJ somewhere near a barber shop on the south bank of the Potomac at 300’ at one mile. Using this landing structure, the CRJ would be around 150’ at mid river, if they were to touch down on the numbers, which I would do, considering the shorter runway, instead of a typical ILS with a runway point of intersection being around 775’ down from the threshold.
I recommend any aviators on this site to take a look at your regular home airport and compare this to DCA’s southern approaches and just where this collision occurred. The Black Hawk could not have been safe at any altitude.
Like C Lynch’s post, it is just inconceivable that this helicopter corridor was approved in the first place.
My next point which is clear to me as a former military and FAA air traffic controller, is that the controller allowed this collision to happen. To use an excuse that the Black Hawk confirmed the CRJ insight and could maintain visual does not relieve the controller of avoiding a collision. ATC and Pilots make mistakes all the time, daily, but it is up to everyone to be on a constant vigil to see, know or realize that something is awry. At five miles apart, I could see this would be a problem. I believe the controller had three aircraft at the time. They have a big radar screen in the tower can, which clearly indicates the aircraft and the altitudes. ATC literally watched them collide. It was very obvious to me after looking at the radar, that this was a problem. Again, 100, 200 or 300’ on their radar, time lapses of flash to bang hitting the target and receiving the response were not a factor.
Finally, as a retired Army Black Hawk pilot, I can guarantee you that flying with NVG’s is extremely tiring and demanding. They are very heavy esp. with the counterbalance pack on the back of the helmet. They would’ve had a head’s up display on the nods to give them altitude info., but it is very difficult at night, I believe, to maintain exactly that altitude so low. They may have had the nods in the up position also, because of the bright lights and the possibility of whiteout. The newer models help prevent that but it is still difficult to see. Field of view is 80 degrees so it is imperative to keep your head on a swivel. A side note is that in my career as a Huey and Black Hawk pilot, I’ve made several airport crossings, but they were always midfield up at altitude. I personally would never accept a crossing at night, nods or not, through a final approach course, not to mention the extreme difficulty of orientation with night VFR (I do not consider night VFR a viable and safe mode of transportation any more) and the possibility of wake turbulence. What was that controller thinking, “fly behind?” No way! If they weren’t restricted to 200’ and could fly over land a few miles to the south I might consider the fly-behind-solution.
One more point which isn’t related to altitudes, is that I personally have visited the Pat VIP unit with the VIP kits installed on the Black Hawks. That was in 1994 when one of my colleagues from flight school was stationed there. They had no CW2’s or WO1’s assigned there, only senior warrant officers because this was the highest VIP unit in the Army. They were in the 2,000 to 5,000 hour level. When I was stationed at Coleman Barracks in the early ‘80’s, flying VIP internationally throughout Europe, WO1’s were not allowed to fly general officers. So to see such low time pilots, flying at the Army’s highest VIP unit, VFR at night through this extremely busy and allegedly very controlled airspace is mind-boggling.
That is all.
February 4
▶ CaptainKirk
Is the “delay” really a contributing factor?
If the data were “real time”, perhaps ATC would be able to notice a trend, but even then, “real time” systems often perform data smoothing-introducing some sort of a delay.
Even if it were a real time update and ATC was focused on the scope, we’d complain that they were too focused on the scope.
If the controllers eyes were out the window, we complain that they were not focused on the scope and hence, missed the trend and/or data.
Every other accident we’d switch our modus to either scope focused or eyes out focused depending on the last accident.
But, here’s the rub: Delay or no delay, scope or no scope, eyes out or in, ATC was aware of the conflict, made the traffic call, the BH acknowledged both the call and the traffic.
The last resort here, would be for the controller to grab the cyclic and collective and steer the BH away from the traffic.
1 reply
February 4
Well, seeing as both aircraft were at the same point in space at the same time, if you can determine what altitude one aircraft was at the time of the collision, you also have the altitude for the other and you can work backwards from there.
February 4
▶ rick.freeman100
Well, I’m the first to admit that I’m not a technical writer nor am I a subject matter expert on this but I do know an editing error when I see one. I tried to fix that line to be more clear and left a few words that should have been cut. I’ll fix.
February 4
In my view, the time lag in the ASR system (ASR-9 or ASR-11), with refresh cycles ranging from 4.9 to 12 seconds, highlights a serious gap in real-time awareness for controllers. As shown by the 125-foot altitude discrepancy in the recent midair collision over the Potomac, even a few seconds of lag can be enough to turn a bad day worse. It shows just how important it is to have better surveillance systems at DCA and across the country, ones that give faster updates, sharper accuracy, and fewer delays.
As air traffic gets busier and more complex, the FAA should double down on replacing these older ASR systems with ones that can handle altitude changes without missing a beat, keeping our skies safer for everyone.
February 5
▶ Robert_Ore
Early in this investigation, the focus was on the controller. Then it switched to the heli’s altitude. Everyone said, wow, it usually take two things gone wrong to cause an accident. True enough, but now there are three things. Helicopter Route 4 specifically shows the corridor follows the extreme eastern bank of the Potomac. The collision happened closer to the western side. So we have a controller who didn’t know the heli’s real altitude, didn’t make note the heli was too far west, a heli pilot who was flying too high, and was out of position. That’s four things wrong, and any one of them could have prevented this accident. Incidentally, the further west the heli flies, the more even his legal altitude becomes an issue.