Pt. 25, App. I

that sense engine failure, transmit signals,
actuate fuel controls or power levers or increase engine power by other means on operating engines to achieve scheduled thrust or
power increases, and furnish cockpit information on system operation.
(b) Critical Time Interval. When conducting
an ATTCS takeoff, the critical time interval
is between V1 minus 1 second and a point on

the minimum performance, all-engine flight
path where, assuming a simultaneous occurrence of an engine and ATTCS failure, the
resulting minimum flight path thereafter
intersects the Part 25 required actual flight
path at no less than 400 feet above the takeoff surface. This time interval is shown in
the following illustration:

I25.3 Performance and System Reliability Requirements.
The applicant must comply with the performance and ATTCS reliability requirements as follows:
(a) An ATTCS failure or a combination of
failures in the ATTCS during the critical
time interval:
(1) Shall not prevent the insertion of the
maximum approved takeoff thrust or power, or
must be shown to be an improbable event.

(2) Shall not result in a significant loss or
reduction in thrust or power, or must be
shown to be an extremely improbable event.
(b) The concurrent existence of an ATTCS
failure and an engine failure during the critical time interval must be shown to be extremely improbable.
(c) All applicable performance requirements of Part 25 must be met with an engine
failure occurring at the most critical point

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