Jet blast and propeller wash
Jet blast (engine exhaust) and propeller wash: ground hazards behind an aircraft. Not wake turbulence (wingtip vortices, generated in flight).
Jet danger area behind tail, by thrust category (TC AIM AIR 1.7, Fig 1.2):
| Category | Thrust | Ground idle | Take-off thrust |
|---|---|---|---|
| Executive jet | up to 15 000 lb | 200 ft | 500 ft |
| Medium jet | up to 35 000 lb | 450 ft | 1 200 ft |
| Jumbo jet | over 100 000 lb | 600 ft | 1 600 ft |
Supersonic transport and military jets:
- No distances published.
- Can have high exhaust velocity for size; may use afterburner on takeoff.
- Use extra caution.
Turbo-prop blast speed (Table 1.6): falls off fast with distance. Take-off thrust by far strongest.
| Distance behind props | Leaving parked | Taxiing | Take-off |
|---|---|---|---|
| 60 ft | 59 kt | 45 kt | N/A |
| 80 ft | 47 kt | 36 kt | 60-70 kt |
| 100 ft | 47 kt | 36 kt | 50-60 kt |
| 120 ft | 36 kt | 28 kt | 40-50 kt |
| 140 ft | 36 kt | 28 kt | 35-45 kt |
| 180 ft | N/A | N/A | 20-30 kt |
Intersecting runways, near active taxiways:
- Expect localized high wind from another aircraft's blast: on ground, taking off or landing.
- Light, high-wing, narrow-track aircraft more susceptible than heavy, low-wing, wide-track.
Trap: blast worst at take-off thrust and close range, not idle. Idle clearance underestimates hazard at take-off power.
References
- TC AIM AIR 1.7