Even if individual drills are used, these are based on the manufacturer's checklists and/or recommendations. And I am pretty much convinced (or more precisely: 100 percent certain) that there is no manufacturer of pressurised aircraft and no training provider who does not put "don oxygen masks" on top of every checklist related to pressurisation problems.

By the way: I just looked up the loss-of-pressurisation followed by emergency descent checklist of the plane I fly today - also a 500 series Cessna but different model from the accident aircraft: Cessna lists "communicate with ATC" as item number 10 on the list.

And regarding "turning away from the airways" before starting the emergency descent: This is not done in Europe since a long time. And makes little sense because one after the other the countries in Europe are getting rid of their airway systems altogether. With all planes flying between waypoints on individual tracks.

Judging from posts here it sounds as if the Rapid Depressurisation and Emergency Descent checklists have not changed in recent years. But those checklists originated many decades ago when high altitude civilian air traffic was very much lighter than today's. The chances of collision resulting from an uncoordinated rapid descent in those years were probably deemed to be infinitesimally small, and therefore acceptable. Perhaps that's no longer a valid deduction.

Anyone knows how long a descend from 36000 feet to 10000 feet takes with speedbrakes in a 551? My gues is <10 minutes. So before a single pilot crawls to the passenger compartment thats what you first do.

Why the BFU?
 

According to news sites, the German BFU will anaylse the accident. Does anybody know why? This wasn't in German airspace, and the aircraft has an Austrian registration, so they shouldn't normally be the state to institute the investigation. The operator is German, but in order of preference, according to ICAO Annex 13, that comes third after the state of registry.

Cheers,
Bernd

Isn't BFU entitled to initiate investigations whenever they feel it might be interesting to them? There is a german owner, PIC, destination, base and all occupants are german to start with.

ICAO Annex 13 regulates that quite clearly.

There are lots of other provisions for tasking other states with the investigation, so maybe Latvia has asked Germany to do it, because they are not as well equipped.

Cheers,
Bernd

In fact it's a moot point as to where the "State of Occurrence" was - the occurrence, for the purpose of Annex 13 being the death of those on board. That could well have happened over Germany.

You can expect around 5000ft/min average rate of descent. Something like five minutes. In the simulator it feels longer...

News reports are just out that the wreckage has been located. And it was confirmed that the aircraft was not equipped with either FDR or CVR. That's going to be a difficult investigation.

An accident is signified by either substantial damage to the aircraft or the death or serious injury of occupants. Since the exact location of the deaths cannot be determined a priori, I don't think anyone would disagree that the location of the accident is taken to be the crash site in this case.

Is there precedent that the location of the deaths was taken as the State of Occurrence instead of the subsequent crash site? I can't remember any accident where that was the case, but I might be wrong.

Cheers,
Bernd

I think it's much simpler than that. The relevant European regulation (*) reads (article 6 para. 2): "2. A safety investigation authority may delegate the task of conducting an investigation into an accident or serious incident to another safety investigation authority subject to mutual agreement and shall facilitate the investigation process by that other authority." Latvia has no connection to this accident other that by pure chance (or bad luck) the aircraft ran out of fuel over Latvian waters.

(*) REGULATION (EU) No 996/2010 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=OJ:L:2010:295:0035:0050:EN:PDF

I think it's common sense to safe guard yourself against hypoxia, if in doubt get the mask on!
But no, there are checklists that involve pressurisation that don't have memory items and don't instruct you to put the mask on. On the 737 a dual pack trip off means your cabin altitude will increase at leakage rate. An unscheduled pressurisation change tells you to increase thrust to ensure air supply to the cabin. None explicitly states where and when to put the mask on. Press. problems can come in different shapes and forms.

The "Establish communication" is with the other pilot (for 2 crew operation), NOT with ATC! Please tell us you knew that and were just trying to wind us up?

EatMyShorts had it exactly right.

Don masks
Establish communication
Emergency descent

Part of the preflight of the Citation series is to check the outside O2 over pressure relief valve or disk.
1. O2 may have been empty
2. O2 may have been turned off
That can probably be verified if the wreckage is brought up.
Anything else what the pilot may or may not have done is conjecture.

in an industry so reliant on redundancies, it surprises me that a portable bottle isn't standard equipment for any pressurised aircraft with a stand up pax cabin (CC background here)

This series of Citations do not have a stand up pax cabin. Space inside the cabin is a little tight, especially when all seats are occupied. The usage of the portable therapeutic oxygen bottle is very difficult in such a confined space, especially for persons not properly trained for it (e.g. paramedics). The company I fly for had them removed many years ago.

There are quite a few things that can be deducted from the state of the wreckage like: Was the pilot's seat belt buckled-up or open? Was his quick donning mask connected to the oxygen outlet? What was the setting of the pressurisation controls - they are mechanical in this aircraft, whatever values were set should still be visible. What position were the switches in that control the pressurisation system? There is a bleed-air selector, an automatic/manual switch and an emergency dump switch. Did the masks in the cabin drop?

SLF and engineer in aerospace industry.
The depressurization report was near Toledo. High ground in central Spain is at about 2500m. A direct line from Jerez de la Frontera to Cologne would take take you over the Pyrenees which has 3000m peaks.
What happens if you have depressurisation whilst flying over high terrain? Could the thought of emergency decent above high terrain delay the decision making perhaps? What altitude would you be comfortable making an emergency descent to, a thousand feet above the highest terrain in the area? Do you pre-plan that emergency descent altitude if the flight plan takes you over high ground? Just curious.

Minimum safe altitude is charted, the pilot doesn't have to guess. 1000ft above the Pyrenees would put you around 11000ft which should be OK for as long as it takes to get somewhere with a lower MSA.

In areas with very high terrain (much higher than Pyrenees), you usually have to plot escape routes in advance and satisfy the regulator before you'll be allowed to plan flights on those airways. For example L888 or Y1, Y2, Y3 in China.

As far as I understand (too many contradicting reports), the final call came at top of climb with actual pressurization issues reported? Why didn't they descend right away? Did the pilot just black out during the call? Were they on masks already?

Absolutely. Not allowed to cross the region otherwise.

Terrain-safe charted altitudes in mountaineous areas provide 2000 ft obstacle clearance.

Anything on recovery attempts?