Page 18
Pilot’s Operating Manual
Revision A1: Nov, 2002
Hawker 800XP Pro Line 21
Section VII - SAFETY INFORMATION
1. Don’t land or take off in the face of an approaching thunderstorm. Sudden gust front low level
turbulence could cause loss of control.
2. Don’t attempt to fly under a thunderstorm even if you can see through to the other side. Turbulence
and windshear under the storm could be disastrous.
3. Don’t fly without airborne radar into a cloud mass containing scattered embedded thunderstorms.
Embedded thunderstorms usually can not be visually circumnavigated.
4. Don’t trust visual appearance to be a reliable indicator of the turbulence inside a thunderstorm.
5. Do avoid by at least 20 miles any thunderstorm identified as severe or giving an intense radar echo.
This is especially true under the anvil of a large cumulonimbus.
6. Do circumnavigate the entire area if the area has 6/10 or greater thunderstorm coverage.
7. Do remember that vivid and frequent lightning indicates the probability of a severe thunderstorm.
8. Do regard as extremely hazardous any thunderstorm with tops 35,000 feet or higher, whether the
top is visually sighted or determined by radar.
If you cannot avoid penetrating a thunderstorm, the following are some do’s BEFORE entering the
storm:
1. Tighten your safety belt, put on your shoulder harness, and secure all loose objects and inform your
passengers.
2. Plan and hold your course to take you through the storm in minimum time.
3. To avoid the most critical icing, establish a penetration altitude below the freezing level or an altitude
where the OAT is -15
°
C or colder.
4. Verify that all heaters and anti-ice/deice systems are on. Icing can be rapid at any altitude and cause
almost instantaneous power failure and/or loss of airspeed indication.
Mountain Flying
Pilots flying in mountainous areas should inform themselves of all aspects of mountain flying, including
the effects of topographic features on weather conditions. Many good articles have been published, and
a synopsis of mountain flying operations is included in the FAA Aeronautical Information Manual, Part 1.
Avoid flight at low altitudes over mountainous terrain, particularly near the lee slopes. If the wind velocity
near the level of the ridge is in excess of 25 knots and approximately perpendicular to the ridge,
mountain wave conditions are likely over and near the lee slopes. If the wind velocity at the level of the
ridge exceeds 50 knots, a strong mountain wave is probable with extreme up and down drafts and
severe turbulence.
The worst turbulence will be encountered in and below the rotor zone, which is usually 8 to 10 miles
downwind from the ridge. This zone is sometimes characterized by the presence of "roll clouds" if
sufficient moisture is present. Altocumulus standing lenticular clouds are also visible signs that a
mountain wave exists, but their presence is likewise dependent on moisture.
