N62NA
Topic Author
Posts: 4011
Joined: Sun Aug 10, 2003 1:05 am

Dispatch Reliability Of AA 777s

Thu Feb 05, 2009 7:04 pm

In the past week I've flown two AA 777s:

AA Flight 56 MIA-LHR
AA Flight 57 LHR-MIA

Flight 56 was delayed about 45 minutes due to some kind of mechanical issue.

Flight 57 was delayed about 2 hours due to no heat in the cockpit, which meant that a valve had to be "taken" from "zone 2" and moved to the cockpit heating system.

When the 777 first came out, I remember reading an article in Airliners magazine that stated that in it's first year, the 777 had a 99%+ dispatch reliability record.

Was I just unlucky, or are the AA 777s, heaven forbid, sinking to the level of the AA A300 reliability?
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Dispatch Reliability Of AA 777s

Fri Feb 06, 2009 2:30 am



Quoting N62NA (Thread starter):
When the 777 first came out, I remember reading an article in Airliners magazine that stated that in it's first year, the 777 had a 99%+ dispatch reliability record.

Was I just unlucky, or are the AA 777s, heaven forbid, sinking to the level of the AA A300 reliability?

AA has 47 777's, so they're flying about 100 flights per day with their fleet. That means they should have about 1 maintenance delay per day on their 777's (with 99% dispatch reliability). So I think you're just unlucky, absent other info.

Tom.
 
LAXintl
Posts: 20183
Joined: Wed May 24, 2000 12:12 pm

RE: Dispatch Reliability Of AA 777s

Fri Feb 06, 2009 3:58 am

Well for the 12months ending 9/08, AA's annual 777 fleet reliabilty stood at 98.25% with an average daily utilization of 11.25hrs.

This is somewhat on the lower end of user experiences, and utilization. Industry average for the 12mos on the -200ER was 99.06%.
From the desert to the sea, to all of Southern California
 
nycbjr
Posts: 118
Joined: Wed Aug 22, 2007 6:45 am

RE: Dispatch Reliability Of AA 777s

Fri Feb 06, 2009 6:25 pm



Quoting LAXintl (Reply 2):
99.06%.

really astonishing when you think of all the parts that have to work in unison, its quite an achievement!

cheers
 wave 
 
N62NA
Topic Author
Posts: 4011
Joined: Sun Aug 10, 2003 1:05 am

RE: Dispatch Reliability Of AA 777s

Sat Feb 07, 2009 1:53 pm



Quoting LAXintl (Reply 2):
Well for the 12months ending 9/08, AA's annual 777 fleet reliabilty stood at 98.25% with an average daily utilization of 11.25hrs.

Then I must have been extremely unlucky (or lucky depending on how you view it) to have incurred those two delays last week!  Smile
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Dispatch Reliability Of AA 777s

Sat Feb 07, 2009 9:01 pm



Quoting Nycbjr (Reply 3):

Quoting LAXintl (Reply 2):
99.06%.

really astonishing when you think of all the parts that have to work in unison, its quite an achievement!

Keep in mind that quite a bit can be not working and still allow dispatch. I'd wager that very few airliners dispatch with all the parts working at the same time.

Tom.
 
nycbjr
Posts: 118
Joined: Wed Aug 22, 2007 6:45 am

RE: Dispatch Reliability Of AA 777s

Sun Feb 08, 2009 8:43 am



Quoting Tdscanuck (Reply 5):
Keep in mind that quite a bit can be not working and still allow dispatch.

right Tom didn't even think about that.. any good resources (online) that lists the things that can be iNop on aircraft?
 
Tristarsteve
Posts: 3365
Joined: Tue Nov 22, 2005 11:04 pm

RE: Dispatch Reliability Of AA 777s

Sun Feb 08, 2009 10:50 am



Quoting LAXintl (Reply 2):
Well for the 12months ending 9/08, AA's annual 777 fleet reliabilty stood at 98.25% with an average daily utilization of 11.25hrs.

This is somewhat on the lower end of user experiences, and utilization. Industry average for the 12mos on the -200ER was 99.06%.

You have to be careful with these figures, the word reliability can mean different things to different folks.
We measure delays for technical reasons. This includes all aircraft that are late (And one minute late is late) due maint. Some of these are just that the technician was busy somewhere else and arrived late to sign off the aircraft! It does not include aircraft that are damaged. Bird strikes and lightning inspections don't count. For main base the figure is around 98.5pc, and on the line about 99.2pc(operated on time). Main base is lower because the MEL is more restrictive, and more work is carried out that can delay the aircraft.
i.e. a major IFE failure would be worked at main base, and a delay taken to fix it., while a line stn with no spares would not work it.
Also weather can affect the numbers! A lot of systems, antice, pitot heat, windscreen heat etc are allowable in the MEL in warm climates but not in the cold.
Reliability can mean number of flights operated, i.e. 99pc reliability means that 1 flight in 100 is canx.
The industry standard for delay reporting is flights that are over 15mins late.

It is very difficult to compare if you don't know the exact criteria used.
 
LAXintl
Posts: 20183
Joined: Wed May 24, 2000 12:12 pm

RE: Dispatch Reliability Of AA 777s

Sun Feb 08, 2009 11:54 pm



Quoting TristarSteve (Reply 7):
You have to be careful with these figures, the word reliability can mean different things to different folks.



Quoting TristarSteve (Reply 7):
It is very difficult to compare if you don't know the exact criteria used.

Numbers are by Boeing and cover overall dispatch reliability, not on time performance.
From the desert to the sea, to all of Southern California
 
doug_or
Posts: 3127
Joined: Sat Mar 18, 2000 9:55 am

RE: Dispatch Reliability Of AA 777s

Mon Feb 09, 2009 12:16 am



Quoting LAXintl (Reply 8):
Numbers are by Boeing and cover overall dispatch reliability, not on time performance.

so does 99% mean it goes out on time 99% of the time or it completes the flight 99% of the time?
When in doubt, one B pump off
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Dispatch Reliability Of AA 777s

Mon Feb 09, 2009 3:17 am



Quoting Nycbjr (Reply 6):
any good resources (online) that lists the things that can be iNop on aircraft?

Indeed there is. The document you're after is the MMEL (Master Minimum Equipment List) and they're all online here (for FAA-certified aircraft):
http://fsims.faa.gov/PICResults.aspx?mode=Publication&doctype=MMEL

If you've never looked at one before, you should read the intro that explains what the columns and codes mean. Basically, the first column identifies the item by ATA code, the second column shows how many items are installed, the third shows how many need to be working, and the fourth provides notes.

Quoting Doug_or (Reply 9):
so does 99% mean it goes out on time 99% of the time or it completes the flight 99% of the time?

It means it leaves on time (within 15 minutes) 99% of the time. Completion percentage is a different measurement. Many airlines are shifting from dispatch reliability to availability, since that's a better measure of airplane reliability.

Tom.

Who is online

Users browsing this forum: No registered users and 11 guests