sudden decompression over atlantic ocean...
Thread Starter
Join Date: Jul 2009
Location: mumbai india
Age: 40
Posts: 11
Likes: 0
Received 0 Likes
on
0 Posts
sudden decompression over atlantic ocean...
Q. what would you do if you experience sudden decompression over cross Atlantic flight from London to NYC and you are more than half way through...
1. Would you continue to your destination?
2. What are the things you will take into consideration?
asked in an airline interview...
1. Would you continue to your destination?
2. What are the things you will take into consideration?
asked in an airline interview...
Registered User **
Join Date: Dec 2010
Location: Botswana & Greece
Age: 68
Posts: 940
Likes: 0
Received 0 Likes
on
0 Posts
Google ETOPS?
I haven't got the memory to give the conclusive answer.
Join Date: Nov 1999
Posts: 2,312
Likes: 0
Received 0 Likes
on
0 Posts
The question is rather vague, which is why it has been suggested you "google ETOP's" I suspect. This will give you an idea of the planning and operational requirements that are used specifically for twin engine extended range operations, but it will also broadly give an understanding of how all aircraft plan for various contingencies in extended range operations.
Your question states, "London to New york and more than half way through." Well that could mean all sorts of things. More than "half way through" might be near the planned destination, in which case the decision is probably a very easy one.
Does it mean half way from a distance standpoint, or halfway from a time standpoint? The answer might generate very different responses.
One thing a decompression does result in, is a descent to an altitude of around 10,000ft. The fuel use at this altitude will be significantly higher than that at the previous altitude. This is one of the specific planning considerations for an extended range dispatch. You must obviously always have fuel to safely divert to an alternate airport at any point in the flight.
The weather at 10,000ft can be a more significant factor than it is at cruising altitudes, and this needs to be taken into account.
Passengers may as a result of the incident need medical attention that in itself necessitates a diversion.
The aircraft itself may have structural or mechanical issues that are causal to the decompression, that necessitates a diversion.
Add these factors up: Fuel, weather, safety and technical, and it is clear that you are going to divert to a planned adequate and suitable airport where your departure or destination airport is not geographically already the best option.
Each extended range flight has it's own specific route considerations that need to be taken into account at both the planning and operational stages.
In the example you give, London to New York, you should remember that this isn't two cities seperated by a vast body of ocean (as people sometime perceive.) Notwithstanding Westerly winds, Jetstreams, etc. The Great circle distance form London to New york is 3451 miles. However only 1980 miles of that is across the open ocean. The great circle route (which on any given day may not be the shortest flight time route,) would take you almost directly overhead Shannon in Eire and Gander Newfoundland in Canada. As such the first 370 miles is largely over a land mass with a lot of potential diversion airports. The last 1100 miles is also over the land mass of Eastern Canada and the Northwestern United States, with similar potential diversionary options.
Distance wise, the half way point on this trip would only be around 600 miles East of Gander or other Newfloundland airports. Time wise (with prevailing Westerly winds) half way would be even closer to these airports.
There are many fixed considerations, that will apply to the planning and operational contingencies for every commercial flight. There are also many dynamic considerations that change on an hourly basis, that also need careful consideration. Fuel loading, weather, airport availibility, aircraft weight and performance, mechanical, medical. The list goes on.
This is a subject that could fill pages and still fail to cover every option, consideration or contingency, but I hope this answer has given you some insight and food for thought.
Your question states, "London to New york and more than half way through." Well that could mean all sorts of things. More than "half way through" might be near the planned destination, in which case the decision is probably a very easy one.
Does it mean half way from a distance standpoint, or halfway from a time standpoint? The answer might generate very different responses.
One thing a decompression does result in, is a descent to an altitude of around 10,000ft. The fuel use at this altitude will be significantly higher than that at the previous altitude. This is one of the specific planning considerations for an extended range dispatch. You must obviously always have fuel to safely divert to an alternate airport at any point in the flight.
The weather at 10,000ft can be a more significant factor than it is at cruising altitudes, and this needs to be taken into account.
Passengers may as a result of the incident need medical attention that in itself necessitates a diversion.
The aircraft itself may have structural or mechanical issues that are causal to the decompression, that necessitates a diversion.
Add these factors up: Fuel, weather, safety and technical, and it is clear that you are going to divert to a planned adequate and suitable airport where your departure or destination airport is not geographically already the best option.
Each extended range flight has it's own specific route considerations that need to be taken into account at both the planning and operational stages.
In the example you give, London to New York, you should remember that this isn't two cities seperated by a vast body of ocean (as people sometime perceive.) Notwithstanding Westerly winds, Jetstreams, etc. The Great circle distance form London to New york is 3451 miles. However only 1980 miles of that is across the open ocean. The great circle route (which on any given day may not be the shortest flight time route,) would take you almost directly overhead Shannon in Eire and Gander Newfoundland in Canada. As such the first 370 miles is largely over a land mass with a lot of potential diversion airports. The last 1100 miles is also over the land mass of Eastern Canada and the Northwestern United States, with similar potential diversionary options.
Distance wise, the half way point on this trip would only be around 600 miles East of Gander or other Newfloundland airports. Time wise (with prevailing Westerly winds) half way would be even closer to these airports.
There are many fixed considerations, that will apply to the planning and operational contingencies for every commercial flight. There are also many dynamic considerations that change on an hourly basis, that also need careful consideration. Fuel loading, weather, airport availibility, aircraft weight and performance, mechanical, medical. The list goes on.
This is a subject that could fill pages and still fail to cover every option, consideration or contingency, but I hope this answer has given you some insight and food for thought.
Join Date: Aug 2008
Location: North America
Age: 64
Posts: 364
Likes: 0
Received 0 Likes
on
0 Posts
.............asked in an airline interview............
The best source for interview preparation I have ever come across are two books by Martin Yate; Answers to tough questions and Hiring the best. I just checked and the author has a web site complete with online services (no I don't work for him or get paid to recommend his services).
While I do not completely agree with his philosophy his extensive background in the business community and experience hiring is vast. I credit his work as being the single most important step in my preparation for landing an extremely competitive job flying for a Fortune 500 company over other highly qualified candidates (years ago). And later on my own "airline interview" was a breeze.
As with just about every worthwhile endeavor it takes time and effort to achieve the desired outcome. There is
more to it than simply showing up in a nice suite of clothes with an impressive looking resume and a few references.
Given your decompression question I might
answer something along the following lines if I were interviewing with a
passenger carrier that markets itself as the top of the line travel experience. The answer may vary a little if it were a smaller start up enterprise hauling freight.
I would say...............
If I had the privilege of being in command and entrusted with the responsibility for a long distance flight for XYZ airline
flying one of your new $@# model jets between point A & point B.
(This lets them know that I value their company (XYZ company) know something of their route structure (flight between point A and point B) and am familiar with the type of equipment that
would normally be used on such a route (your new $@# model jets).
If during such a flight we were faced with a decompression event, I would first positively identify the problem. A rapid decompression event should show a high rate of climb indicated in the cabin rate of climb indicator, followed by an immediate increase in cabin altitude (decrease in cabin pressure). There may also be a loud noise followed by rapid condensation in the cabin depending on the severity of the decompression.
After correctly identifying the problem I would immediately accomplish your airline training department’s memory items which I would expect to include.
1. Oxygen mask on, 100% oxygen delivery, and emergency
position.
2. Crew communications establish.
3. Followed by whatever else, if any, is on the immediate action memory items to include verifying deployment of the passenger’s oxygen
masks.
While that is being done we need to take care of the passengers and airplane, that means getting down to a safe altitude. Now is the time to make sure both pilots are aware of the terrain, if any, below and what the minimum safe altitude is and where if any are the terrain threats. There are a few things to consider as we point the nose down
and begin the emergency descent.
The rapid decompression checklist should take you to the emergency descent checklist. If the jet were on an established track it would involve getting a safe distance off the track so as to minimize diving down and into opposing traffic. Once the correct distance from the track is achieved we would turn to parallel the track in the direction we intend to go. All the exterior lights would be turned on and we would make every attempt to contact ATC, or whatever authority has jurisdiction over the airspace, to notify them and oursurrounding traffic of our emergency and what actions we are taking. Now is the time to use the Mayday, Mayday, Maday call.
The Aloha Airlines 737 explosive decompression accident of the early 80s taught us to make sure to assess the structural integrity of the jet prior to commencing a maximum airspeed emergency descent.
“Proper prior preparation prevents (piss – would probably leave that one out during the formal interview) poor performance”; now is the time that having made the effort to keep track of one’s position relative to the next CP (Critical Point) distance to suitable alternates, what services are available and the current weather will reap tremendous dividends.
Fortunately XYZ airline has made the investment and given me the tools necessary like satellite, ACARS and/or HF to consult with other resources, like dispatch control and ATC, who may have information and resources not currently available to me, that will assist me in making the safest and best decision in taking care of our passengers.
Using all the resources available to me; preflight planning, ATC, dispatch control, the flight attendants to ascertain the condition of the passengers and what medical service providers may be on the jet, the autopilot and other pilot in planning workload management as tasks will need to be accomplished and control of the jet may never be compromised.
In the mean time the jet is heading to the nearest suitable alternate which may, or may not be on the flight plan, at the ETOPS divert speed schedule (it could be the stated alternate or even continuing to the destination) preferably with a clearance. The routing will depend on surrounding traffic whether or not a clearance is obtained, condition of the aircraft and the passengers. We could be paralleling tracks, navigating to join other tracks or even direct under some circumstances.
After the safe landing I would make every effort to take care of the passenger’s immediate medical needs followed by their accommodation and other predictable needs to the best of my ability. If possible I would try to arrange separate accommodations for the rest of the crew away from the jet/airport. I would stay with the aircraft and make myself available to the passengers and local authorities until I was relieved by a representative of XYZ airline.
Then I would shut up, smile and listen very carefully to any feedback and critique acknowledging whatever improvements were offered; the object is to get the job offer, not to get into a defensive argument.
While I do not completely agree with his philosophy his extensive background in the business community and experience hiring is vast. I credit his work as being the single most important step in my preparation for landing an extremely competitive job flying for a Fortune 500 company over other highly qualified candidates (years ago). And later on my own "airline interview" was a breeze.
As with just about every worthwhile endeavor it takes time and effort to achieve the desired outcome. There is
more to it than simply showing up in a nice suite of clothes with an impressive looking resume and a few references.
Given your decompression question I might
answer something along the following lines if I were interviewing with a
passenger carrier that markets itself as the top of the line travel experience. The answer may vary a little if it were a smaller start up enterprise hauling freight.
I would say...............
If I had the privilege of being in command and entrusted with the responsibility for a long distance flight for XYZ airline
flying one of your new $@# model jets between point A & point B.
(This lets them know that I value their company (XYZ company) know something of their route structure (flight between point A and point B) and am familiar with the type of equipment that
would normally be used on such a route (your new $@# model jets).
If during such a flight we were faced with a decompression event, I would first positively identify the problem. A rapid decompression event should show a high rate of climb indicated in the cabin rate of climb indicator, followed by an immediate increase in cabin altitude (decrease in cabin pressure). There may also be a loud noise followed by rapid condensation in the cabin depending on the severity of the decompression.
After correctly identifying the problem I would immediately accomplish your airline training department’s memory items which I would expect to include.
1. Oxygen mask on, 100% oxygen delivery, and emergency
position.
2. Crew communications establish.
3. Followed by whatever else, if any, is on the immediate action memory items to include verifying deployment of the passenger’s oxygen
masks.
While that is being done we need to take care of the passengers and airplane, that means getting down to a safe altitude. Now is the time to make sure both pilots are aware of the terrain, if any, below and what the minimum safe altitude is and where if any are the terrain threats. There are a few things to consider as we point the nose down
and begin the emergency descent.
The rapid decompression checklist should take you to the emergency descent checklist. If the jet were on an established track it would involve getting a safe distance off the track so as to minimize diving down and into opposing traffic. Once the correct distance from the track is achieved we would turn to parallel the track in the direction we intend to go. All the exterior lights would be turned on and we would make every attempt to contact ATC, or whatever authority has jurisdiction over the airspace, to notify them and oursurrounding traffic of our emergency and what actions we are taking. Now is the time to use the Mayday, Mayday, Maday call.
The Aloha Airlines 737 explosive decompression accident of the early 80s taught us to make sure to assess the structural integrity of the jet prior to commencing a maximum airspeed emergency descent.
“Proper prior preparation prevents (piss – would probably leave that one out during the formal interview) poor performance”; now is the time that having made the effort to keep track of one’s position relative to the next CP (Critical Point) distance to suitable alternates, what services are available and the current weather will reap tremendous dividends.
Fortunately XYZ airline has made the investment and given me the tools necessary like satellite, ACARS and/or HF to consult with other resources, like dispatch control and ATC, who may have information and resources not currently available to me, that will assist me in making the safest and best decision in taking care of our passengers.
Using all the resources available to me; preflight planning, ATC, dispatch control, the flight attendants to ascertain the condition of the passengers and what medical service providers may be on the jet, the autopilot and other pilot in planning workload management as tasks will need to be accomplished and control of the jet may never be compromised.
In the mean time the jet is heading to the nearest suitable alternate which may, or may not be on the flight plan, at the ETOPS divert speed schedule (it could be the stated alternate or even continuing to the destination) preferably with a clearance. The routing will depend on surrounding traffic whether or not a clearance is obtained, condition of the aircraft and the passengers. We could be paralleling tracks, navigating to join other tracks or even direct under some circumstances.
After the safe landing I would make every effort to take care of the passenger’s immediate medical needs followed by their accommodation and other predictable needs to the best of my ability. If possible I would try to arrange separate accommodations for the rest of the crew away from the jet/airport. I would stay with the aircraft and make myself available to the passengers and local authorities until I was relieved by a representative of XYZ airline.
Then I would shut up, smile and listen very carefully to any feedback and critique acknowledging whatever improvements were offered; the object is to get the job offer, not to get into a defensive argument.
Last edited by Northbeach; 26th Jul 2011 at 06:45. Reason: Markerinbound corrected a mistake on my part, deleted the 10 nm numerical reference that was incrorrect
ICAO has for a long time issued the NAT Doc 007 MNPS manual which details planning for NAT operation and contingency procedures. The importants bits are also printed on the Jeppesen NA H/L 1-2 Chart. Anyone who has flown, or intends to fly the NAT area should be familiar. Google and behold.
In short, if on a NAT track you turn perpendicular to the track for your emergency descent, declare emergency and request a clearance to proceed to the nearest suitable airport (which might be SNN, KEF, YQX, YYR, etc). You would probably not continue unpressurized at 10,000 ft to your destination. I definitely would not, and I have been plying the Atlantic for quite a while.
In short, if on a NAT track you turn perpendicular to the track for your emergency descent, declare emergency and request a clearance to proceed to the nearest suitable airport (which might be SNN, KEF, YQX, YYR, etc). You would probably not continue unpressurized at 10,000 ft to your destination. I definitely would not, and I have been plying the Atlantic for quite a while.
Last edited by oceancrosser; 24th Jul 2011 at 00:50.
