Unresponsive C560
 

A Cessna C560 that has been unresponsive to ATC has crashed in Staunton Virginia. A number of air-defence assets were launched to intercept it.The aircraft was heading from Elizabethton, TN to Ronkonkoma, NY (Suffolk County) and was approaching DC and was unresponsive to Air Traffic Control, causing fighter jets from Andrews AFB to approach the Cessna.

DC Sonic Boom/Citation Down in VA
 

Sonic boom heard across D.C. region caused by military flight, Md. officials say

That's the headline. In the article (link below) it is said a Cessna Citation was reported down after having flown over DC.

https://www.washingtonpost.com/dc-md...ginia-maryland

Boom shook the house around 3:11 p.m. local.

I saw elsewhere that the plane had made it to near its planned destination and circled round, flying back towards the southwest and MD-DC, was unresponsive, and was in restricted air space near the White house. Fighter jets were scrambled to intercept a potential threat. Some speculation the jet was shot down, unconfirmed. The other obvious theory is pilot incapacitation due to medical emergency such as heart attack or hypoxia.

Numerous region-wide reports of a sonic boom (from the fighter jets, presumably).

Flightaware shows aircraft (N611VG) never initiated a decent approaching ISP destination, maintaining cruise altitude of FL340 through course reversal to SW. Track continued to the SW at FL340 across DC, passing to the N of P-56 areas, but those prohibited areas extend up to only 18,000 ft.

Interesting to view the flight path - but what would cause it to loop back around like that?
I presume the flight plan would have taken it as far as Suffolk County airport... but why a U-turn?

Would be interesting to see what the default behavior of the C560 FMS is after completing its route without landing and remaining on autopilot. Perhaps it was simply heading to the departure waypoint. Or perhaps there was some fragment of a flight plan beyond KISP that included the departure aircraft (or something else along that line). Or perhaps it wasn't heading to any particular waypoint at all, just a heading direction that pointed back to the origin direction. Very puzzling behavior for an FMS. At any rate, it flew inbound to but above the SFRA/FRZ near Washington DC and caused quite a stir.

Despite the tragedy for those aboard, it is fortunate that the plane crashed in the national forest in a very remote area. With additional fuel, it may easily have crashed closer to whatever waypoint/direction it was heading to and in a populated area, causing something even worse, unless the fighter jets decided to shoot it down first.

This was a 1990 model, so the original Citation V before the later upgrades (Ultra than Excel).

More details to come....

Sounds a lot like the one that ended in the Baltic sea last year.
https://en.wikipedia.org/wiki/2022_B...Citation_crash

More information about the owners and occupants, the political “twist” will no doubt result in a few conspiracy theories. May they rest in peace.

N611VG Owners

Aviation Safety Network's succinct summary: https://aviation-safety.net/database...?id=20230604-0

On more modern aircraft are there design/regulatory mandates to override the throttles when the cabin pressure goes over 10,000 feet? It seems obvious enough. How many crashes would have been avoided by such a mechanism?

Please can you elaborate on what you mean/are suggesting?

If the cabin pressure gets above 10,000 feet (or some other agreed upon value) that the engines throttle back to a setting appropriate for cruise at that altitude.

I think it would have saved at least 3 aircraft that I know of - all turned into long-range cruise missiles waiting to drop on unsuspecting landscape. Lucked out so far they have missed cities.

There is likely some pressurization warning but it seems not to be reliable or sufficient.

Isn't it premature to conclude that the pilot passed out due to an absence of pressurisation ?

Sure. And no other occupants were seen waving. Just like every other pressurization failure. But maybe they all had the fish,

There are later Citation 560 models (the 560XLS and XLS+) whose autopilot has an automatic emergency descent mode. One prerequisite for that are electronically controllable engines (FADEC) which this 1990 model did not have, unless retrofitted at some later stage.
But there is a much easier and non-technical way by which some of these accidents, including the one over the Baltic Sea referenced above, can be prevented: Employ a second pilot. Money seems to have been no issue here, the aircraft owners could even afford to donate hundreds of thousands of Dollars to politicians. What are a few hunderd Dollars per flight in comparison to that?

I was remarking on it being required, not if it was available. Typical hypoxia causes** lead to the victims having no idea of the seriousness of the problem, so they would never start an emergency response. They should already have oxygen available - they just don't choose to use it.

**In the non-aviation cases it occurs when some volume is filled with atmosphere displacing gases. One horror story was a rail road tank car that a guy was sent to clean out. His buddy noticed he had taken too long and went to the car, climbed up and, looking down the hatch, saw the guy motionless at the bottom. So his buddy climbed in to help, and also died. They get confused, often giddy, and then die. A second pilot might not help.

There are some very few cases where an external help saved the day.
I would hope (or recommend) that all controllers here have listened to the audio recording underneath and be able to recognise hypoxic incapacitation.

<iframe width="969" height="646" src="https://www.youtube.com/embed/XGdYb2J6Wbk" title="What a Pilot Sounds Like With Extreme Hypoxia" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" allowfullscreen></iframe>

https://www.youtube.com/watch?v=XGdYb2J6Wbk

There are areas of the Earth where that would put you into the side of a mountain.

What I do think would help is if all pilots of pressurised aircraft were subjected to a hyperbaric chamber. They would then know the warning signs of a slow depressurisation, and be able to act accordingly.