曝光台 注意防骗
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Advisory Circular 150/5390-2, Heliport Design.
The visibility minimum is based on the distance from
the MAP to the heliport, among other factors, e.g.,
height above the heliport elevation when at the MAP
MDA. The pilot is required to acquire and maintain
visual contact with the heliport final approach and
takeoff (FATO) area at or prior to the MAP. Obstacle
or terrain avoidance from the MAP to the heliport is the
responsibility of the pilot. If the required weather minimums do not exist, then the published missed
approach procedure must be executed at the MAP
because IFR obstruction clearance areas are not applied
to the visual segment of the approach and a missed
Point-in-Space Approach Examples
Example 1:
Under Part 91 the operator flies the published IFR PinS approach procedure that has a charted MDA of 340
mean sea level (MSL) and visibility of 3/4 SM. When approaching the MAP at an altitude of 340 feet MSL
the pilot transitions from Instrument Meteorological Conditions (IMC) to Visual Meteorological Conditions
(VMC) and determines that the flight visibility is 1/2 SM. The pilot must determine prior to the MAP whether
the applicable basic VFR weather minimums can be maintained from the MAP to the heliport or execute a
missed approach. If the pilot determines that the applicable basic VFR weather minimums can be
maintained to the heliport the pilot may proceed VFR. If the visual segment is in Class B, C, D, or the surface
area of Class E airspace, it may require the pilot to obtain a Special VFR clearance.
Example 2:
For an operator to proceed VFR under Part 135, a minimum visibility of 1/2 SM during the day and 1 SM at
night with a minimum ceiling of 300 feet. If prior to commencing the approach the pilot determines the
reported visibility is 3/4 SM during the day the pilot descends IMC to an altitude no lower than the MDA and
transitions to VMC. If the pilot determines prior to the MAP that the flight visibility is less than 1/2 SM in the
visual segment a missed approach must be executed at the MAP.
Figure 7-16. Point-in-Space Approach Examples.
7-17
approach segment protection is not provided between
the MAP and the heliport. As soon as practicable after
reaching the MAP, the pilot advises ATC whether cancelling IFR and proceeding visually, or executing the
missed approach.
INADVERTENT IMC
Whether it is a corporate or HEMS operation, helicopter pilots sometimes operate in challenging weather
conditions. An encounter with weather that does not
permit continued flight under VFR might occur when
conditions do not allow for the visual determination of
a usable horizon (e.g., fog, snow showers, or night
operations over unlit surfaces such as water). Flight in
conditions of limited visual contrast should be avoided
since this can result in a loss of horizontal or surface
reference, and obstacles such as wires become perceptually invisible. To prevent spatial disorientation, loss
of control (LOC) or CFIT, pilots should slow the helicopter to a speed that will provide a controlled
deceleration in the distance equal to the forward visibility. The pilot should look for terrain that provides
sufficient contrast to either continue the flight or to
make a precautionary landing. If spatial disorientation
occurs, and a climb into instrument meteorological conditions is not feasible due to fuel state, icing conditions,
equipment, etc., make every effort to land the helicopter
with a slight forward descent to prevent any sideward or
rearward motion.
All helicopter pilots should receive training on
avoidance and recovery from inadvertent IMC with
emphasis on avoidance. An unplanned transition
from VFR to IFR flight is an emergency that involves
a different set of pilot actions. It requires the use of
different navigation and operational procedures,
interaction with ATC, and crewmember resource
management (CRM). Consideration should be given
to the local flying area’s terrain, airspace, air traffic
facilities, weather (including seasonal affects such
as icing and thunderstorms), and available
airfield/heliport approaches.
Training should emphasize the identification of circumstances conducive to inadvertent IMC and a
strategy to abandon continued VFR flight in deteriorating conditions.
3
This strategy should include a
minimum altitude/airspeed combination that provides for an off-airport/heliport landing, diverting
to better conditions, or initiating an emergency
transition to IFR. Pilots should be able to readily
identify the minimum initial altitude and course in
order to avoid CFIT. Current IFR en route and
approach charts for the route of flight are essential.
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Instrument Procedures Handbook (IPH)仪表程序手册下(159)
