Just for some general details, I have no clue what happened with this one.
We normally start the engines while pushing using the Auxiliary power unit (APU) for the air source. there is only one person attached or near the aircraft out the front nobody near the hull.
When the APU is broken, we use a ground start cart which pumps out high volume of air at about 40 psi.
You start one engine on stand clear the ground starter and then start the other one via cross bleed while pushing back using the started engine.
From what I can see this occurred on stand with an Embraer with the parking brake on, I don't have a clue where the attachment points are for them or what the start sequence is for the engines. But I suspect it was a start one and the cross-bleed start on push. It's extremely rare to do this to be honest I have 1400 hours now on A220 and have done this once in real life and maybe 3 times during type rating and recurrent training in 3 years. The ground handlers won't be very currant doing it either.
So they started one engine and then had to remove electrical and ground air start units. The electrical will be forward somewhere near the nose gear. The air start port is usually near the wing root which is just next to the danger area of the engine intake. In Europe there is a warning sign on the inside face of the engine using pictorial warning. While disconnecting the start air this accident occurred.
I am really not sure what practical training the groundcrew get for doing them to be honest if any. It costs about 500 bucks to start an engine in capital cycle costs and fuel.
Very sad and thankfully it is extremely rare occurrence.
Yes. I've always noticed the warning signs, but this is the first time I've ever heard of this actually happening. An extreme black swan event, but there it is.
Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."
The aerials of the airport don't show good (or any) safety distances painted on the ground.
Plenty of comments below the videos from workers saying that they witnessed near misses on multiple occasions, not at this airport in particular, but others that have a similar mode of operation.
FAA and NTSB reports will be out soon, but it shows how difficult it is to reduce risk in things like this which become so regular to those doing it that relying on procedures all the time can lead to such a horrible way to go.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
It's the APU not working which throws a colossal spanner in the works. It significantly changes the normal procedures for everyone.
It's likely the ground power is on the air bridge under it so to get it attached to the aircraft they should come in from the nose, but if the bridge isn't attached yet then that takes them into the danger cone in front of the engine.
A flight crew error is keeping both engines on while parked waiting. APU also provides hydraulic power and power for other ground services brakes etc but it depends on the aircraft type. A220 I don't lose anything shutting one engine down without the APU on. There is two main AC hydraulic pumps and PTU between the two main Hydraulic systems and then another 3 backup electric pumps one of which is DC off that bus. The flight controls have another backup system which remains hidden until it's in use. The brakes are electric which causes different issues with the APU not working. But these model differences the ground crew can't be expected to know.
Also, to note as well things change in low temp conditions the cowl anti ice might be on which increases the N1 fan speed which generates more suction.
The manual shows an engine idle safety zone of 2.5m / 8.5 ft arc from the centre of the engine.
There doesn't seem to be a lot of space between this and the air bridge so a moments inattention to detail and that's your hole in the swiss chees gone.
It is a bit surprising that no one has figured out a safer way of doing ground operations when engines are running though.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
There is methods that does work. But 99% of the time the APU is working and its never an issue.
Newer types, things are setup differently so there is no issue shutting down the left engine. Which is what we do on the A220, sometimes I don't start the APU because I know we can do it safely. But only in certain airports eg Helsinki or Schiphol, would never attempt it in say a Greek island. I just shut down the Left engine while taxing the turn coordinator plugs into the forward coms port and I confirm LH engine off clear attach GPU and dock the air bridge. Reply front chocks in wilco. Then after 60 seconds we get the light come on in the cockpit external power available. Press the button then kill the RH engine then beacon off. And single engine taxi is banned in icing conditions.
To note though there is no requirement for me to have a working APU to do single engine taxi. I know that on other aircraft types you're not allowed to do it with a MEL APU. a220 One engine powered generator online can provide enough power, to power the whole ship and there is backup to power the brakes.
Also that safety cone is idle thrust without ice protection on. Which would have a N1 of about 25% if I have cowl icing on it will go up to 35% and if I am taxing single engine without the APU it will be around 32% without cowl icing on.
With 78 seats I presume it's a EMB135 which is quite a short aircraft and due to being a swept wing jet there will be less room between the pod and the nose connection points than say a Q400 turboprop with 72 seats.
The first hole in slice of cheese is the APU being broken we shall see what the report says about the rest of it.
And you really don't want to be anywhere near the technicians when they are doing engine runs with the cowls up. They crawl all over the things while running and sometimes quiet high power settings. I can't watch and utterly hate being in the cockpit while they are doing it. Thankfully in my current company Pilots are banned from being used for technical engine runs.
The cold weather higher idle power thing may be something as well - there was a second distance of around 4.2m / 14ft for what they called "breakaway power"
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
normally the fuel is cut inside 5 seconds after the aircraft halts.
Parking brake ON, nose steering off, left engine off, right engine off, beacon off seatbelts off.
So there is habitual behaviour at play here as well if the engines are running for a couple of minutes after the aircraft has stopped. Normally 5 seconds and your safe. Some engines also do a purge of the fuel nozzles which increases the N1 for a couple of second's burst.
The beacon is on top of the Hull and between the gear down low and hard to see close in on the ground.
To be honest it wouldn't be an overreaction to require airside safety ops to be present on any stand with No APU operations. Just as an oversite watching where the ground crew are going and make sure everyone is reminded of the additional risk factors.
FWIW- At the time of the accident the ground temperature in Montgomery, Alabama was about 68 F/ 20 C. Also, Montgomery is a small/lightly served regional airport.
Ok ignore the cowl icing stuff at 20 deg's it needs to be used up to +10 degs air temp.
In Europe there is no difference between the airside safety requirements whatever size of airport. The airport either is licensed for commercial air transport or its not.
The unfortunate female was apparently a baggage handler so may not have known that the engines would need to keep running as there was a need to plug in the power connection due to an apparently malfunctioning APU.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
I don't have a clue what's required in the USA but I have just today completed my Airside Safety Qualification which was an hour of CBT and a 20 question online exam. I have to do it every two years. Most of it was stuff I never go near so I have to watch the CBT properly to answer the questions. Airport security is tomorrow's ballache.
Its a common course for everyone that has an airside pass be it cabin crew through to the very well paid "technicians" that drive the honey wagon aka toilet service vehicle... and some do struggle with it as they have to learn the apron markings which are extremely lacking in the picture above.
Over here it takes about 2 weeks for the relevant courses to be completed and then they start OJT and they get a different coloured High Viz vest until they have been signed off as competent. Which I will admit works very well. I have spotted a couple of them looking lost on the ramp and gone and rescued them. And much to their surprise it didn't result in a colossal telling off and since then I always get a wave and they will come and tell me if something is different.... which I might add hasn't resulted in them saving the day yet but I like the fact communication is open and nobody is scared to approach me.
As the video you posted says they shouldn't approach the aircraft until the beacon is off.
It may be that FAA has offloaded the airport safety oversite to a locally paid FAA representative similar to the aircraft certification. That representative would have had the pre OJT instruction requirement and the airport markings under their remit. But I really don't know what's required in the USA if anything.
Airlines don't muck around with this sort of stuff either. It's a lot of money for a new engine and insurance companies are very particular about get out clauses. Airports EU airlines fly to get audited by their QA departments and routes have been cancelled when they have had findings that they have refused to sort out. Which doesn't help the airport because that's then reported to EASA which then tackles the local CAA and they have to sort it out anyway.
As I said before this sort of accident is extremely rare and the limited number I have heard about the APU not working is nearly always a feature.
Thanks for your insights Alistair. Of course what is required and what is done sometimes are separate things. And workers don't always behave as they have been trained, especially when faced with a nonroutine circumstance. I expect when the investigation comes out it will identify at least 1 human factor as a contributing cause, since the (speculative) scenario we have laid out may be unamenable to extensive engineering- or process controls.
I mention the regional airport because (like any organization) they MAY have less resources (e.g. fewer workers having to do multiple tasks, less worker experience from fewer flights) and less oversight (especially peer-to-peer) potentially adding to the hazard stack / holes in the cheese leading up to an incident such as this, regardless of compliance with the same regulations as larger airports. Maybe that's a more general safety observation I can apply in my own (non-aerospace) industry from this tragedy.
We have air filters on gas turbine inlets, so why isnt there a coarse sturdy mesh guard at the air intakes to jet engines? It would hardly impede air flow to the engine. That would have stopped large objects from getting pulled into air intakes.
