Question

the southwest flight accident was a being 737 equipped with two engines. it was designed with full redundancy for landing purpose, (it can land with only one working engine). Assuming that the engine has a failure rate of 0.0001 per hour and the average flight time is 2 hours

a) what are the system reliability and the equivalent system failure rate as far as landing is concerned( assuming no other failure is possible)?

b) Assuming that in average every 6 seconds around the clock, there is one Being 737 landing to an airport somewhere in the world, estimate the number of potential Being 737 landing accidents over a period of 10 years in the world (considering only the engine problem)

Answer 1

A.

a) what are the system reliability and the equivalent system failure rate as far as landing is concerned( assuming no other failure is possible)?
Per engine
Failure rate	0.0001	Per hour
Failure rate for a flight (2 hours)	0.0002	Per flight
R =Reliability = 1- Failure rate	0.9998	Per flight
As this is parallel process
Net Reliability
R net = 1-(1-R)*(1-R)	0.9999999600	Per flight
So failure rate = 1-Rnet	0.0000000400	Per flight

B.

b) Assuming that in average every 6 seconds around the clock, there is one Being 737 landing to an airport somewhere in the world, estimate the number of potential Being 737 landing accidents over a period of 10 years in the world (considering only the engine problem)
Total seconds in 10 years (Assuming 365 days)	315360000	(10*365*24*3600)	Seconds
N =No of flights landing in 10 years = Total sec/6	52560000		Landings
F = Failure rate as calculated in A	0.0000000400
No of accidents = F*N	2.102399999

So no of accidents in 10 years is

2.102399999