COPTER GPS APPROACHES TO AN AIRPORT OR HELIPORT
Pilots flying Copter GPS or WAAS SIAPs must limit
the speed to 90 KIAS on the initial and intermediate
segment of the approach, and to no more than 70
KIAS on the final and missed approach segments. If
annotated, holding may also be limited to 90 KIAS to
contain the helicopter within the small airspace provided
for helicopter holding patterns. During testing
for helicopter holding, the optimum airspeed and leg
length combination was determined to be 90 KIAS
with a 3 NM outbound leg length. Consideration was
given to the wind drift on the dead reckoning entry leg
at slower speeds, the turn radius at faster airspeeds,
and the ability of the helicopter in strong wind conditions
to intercept the
inbound course prior to the
holding fix. The published
minimums are to be used with
no visibility reductions
allowed. Figure 7-12 on page
7-13 is an example of a
Copter GPS PinS approach
that allows the helicopter to
fly VFR from the MAP to the
heliport.
The final and missed approach
protected airspace providing
obstacle and terrain avoidance
is based on 70 KIAS, with a
maximum 10-knot tailwind component. It is absolutely
essential that pilots adhere to the 70 KIAS limitation in
procedures that include an immediate climbing and
turning missed approach. Exceeding the airspeed
restriction increases the turning radius significantly,
and can cause the helicopter to leave the missed
approach protected airspace. This may result in controlled
flight into terrain (CFIT) or obstacles.
If a helicopter has a VMINI greater than 70 knots, then it
will not be capable of conducting this type of approach.
Similarly, if the autopilot in “go-around” mode climbs
at a VYI greater than 70 knots, then that mode cannot
be used. It is the responsibility of the pilot to determine
compliance with missed approach climb gradient
requirements when operating at speeds other than VY
or VYI. Missed approaches that specify an “IMMEDIATE
CLIMBING TURN” have no provision for a
straight ahead climbing segment before turning. A
straight segment will result in exceeding the protected
airspace limits.
![](images/chapter_11_2.jpg)
Protected obstacle clearance areas and surfaces for the
missed approach are established on the assumption that
the missed approach is initiated at the DA point and for
nonprecision approaches no lower than the MDA at the
MAP (normally at the threshold of the approach end of
the runway). The pilot must begin the missed approach
at those points! Flying beyond either point before
beginning the missed approach will result in flying
below the protected OCS and can result in a collision
with an obstacle.
The missed approach segment TERPS criteria for all
Copter approaches take advantage of the helicopter’s
climb capabilities at slow airspeeds, resulting in high
climb gradients. [Figure 7-13 on page 7-14] The OCS
used to evaluate the missed approach is a 20:1 inclined
plane. This surface is twice as steep for the helicopter as the OCS used to evaluate the airplane missed
approach segment. The helicopter climb gradient is
therefore required to be double that of the airplane’s
required missed approach climb gradient.
![](images/chapter_11_3.jpg)
A minimum climb gradient of at least 400 feet per NM
is required unless a higher gradient is published on the
approach chart; e.g., a helicopter with a ground speed
of 70 knots is required to climb at a rate of 467 feet per
minute (FPM)2. The advantage of using the 20:1 OCS
for the helicopter missed approach segment instead of
the 40:1 OCS used for the airplane is that obstacles that
penetrate the 40:1 missed approach segment may not
have to be considered. The result is the DA/MDA may
be lower for helicopters than for other aircraft. The
minimum required climb gradient of 400 feet per NM
for the helicopter in a missed approach will provide 96
feet of required obstacle clearance (ROC) for each NM
of flight path.
2467 FPM = 70 KIAS x 400 feet per NM/60 seconds
|