Embraer 190 - Page 333

PERFORMANCE
AIRPLANE
FLIGHT
MANUAL
5-01
CTA APPROVED
Page 18 code 01
ORIGINAL
AFM-1912
TAKEOFF MAXIMUM STOPPING MARGIN
The use of minimum V
1
has long been understood to be a valuable aid
in the prevention of rejected takeoff (RTO) overrun accidents. The
minimum V
1
provided by the CAFM will be the lowest V
1
for the
RTOW. As such, it will provide the greatest margin between the
accelerate-stop distance available and the accelerate-stop distance
required. For airplanes with relatively low ground minimum control
speeds, the lowest permissible V
1
may be as such as 40 knots below
the rotation speed, V
R
. This puts the pilot into a position of having to
continue a takeoff following an engine failure at a very low speed.
The input parameters provided in boxes “Maximum stopping margin”
and “Maximum difference between V
1
and V
R
” are intended to allow
the airline user to take advantage of the benefits provided by the use
of minimum V
1
while at the same time reducing the exposure time
between V
1
and V
R
to suit his needs.
As actual takeoff weight is reduced below the field length limited
weight (FLLW) there is a range of V
1
speeds defined by V
1
MIN and V
1
MAX. The greatest stopping margin is provided when V
1
= V
1
MIN. At
relatively low actual takeoff weights the stopping margin provided by
V
1
MIN may be much greater than the required to provide reasonable
protection for an RTO overrun. There is a corresponding large
exposure time between V
1
and V
R
where a takeoff would have to be
continued following an engine failure.
Maximum difference between V
1
and V
R
(!V) allows the user to limit
the calculation of V
1
MIN as follows: as actual takeoff weight is
reduced below the FLLW the calculation of V
1
MIN proceeds normally;
at the point where V
1
MIN is equal to V
R
– !V, then the calculation of
V
1
MIN is governed by the specified speed difference.
Maximum stopping margin allows the user to limit the calculation of
V
1
MIN as follows: as actual takeoff weight is reduced below the
FLLW, the calculation of V
1
MIN proceeds normally; at the point where
the specified stopping margin is reached, the calculation of V
1
MIN is
governed by the stopping margin, i.e., V
1
MIN is increased in order to
keep the stopping margin. V
1
MIN will not be allowed to be greater
than V
1
MAX (V
R
or V
MBE
).