AROTA
Approach
Approach rule of thumbs
Approach speed during gusts
In gusty conditions, add half of the gust factor to your approach speed.
Additional speed = (Gust strength - wind strength)/2
During gusting conditions, airspeed fluctuates. Increasing approach speeds adds a factor of safety in case of an unexpected drastic decrease in airspeed. Gust factor: For example, when it is reported that winds are 10 knots gusting till 30, the gust factor would be 20 knots (30 - 20). Example: If your aircraft approach speed is 80 knots, adding 10 knots (Gust factor/2) to approach at 90 knots adds a layer of safety during the approach.
Predicting Low Level Wind Shear (LLWS)
Winds at around 2000ft are >20 knots and surface level winds are <10 knots
OR
Wind direction changes drastically >60°
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Wind shear is a sudden change of wind direction or/and wind strength. Low level wind shear is a threat during approach to landing as it affects aircraft performance at a critical phase of flight. Horizontal wind shear: Change of wind direction or/and strength over a horizontal distance Vertical wind shear: Change of wind direction or/and strength over height For example, an aircraft on approach encounters horizontal wind shear, a change of wind component to an increased headwind (increasing performance shear); IAS and lift production increases and the aircraft climbs above the glideslope. If corrective or predictive action is not applied, the aircraft may touch down at a high speed and too late, risking a runway excursion or overshooting the runway. *I recommend further reading to fully understand the effects of performance shear: https://skybrary.aero/articles/performance-shear
Estimating height while on a 3° glideslope
Height above ground level (AGL) = Distance to touchdown x 300ft
Using the 1 in 60 rule, we can approximate our height above ground. Example: We are fully established on a 3° ILS 3NM away from touchdown. Our approximate height above ground = 3 x 300 = 900ft. To know our altitude, simply look at the altitude indicator, or approximate it by adding the touchdown elevation + 900ft. *For other angles, adjust the 300ft factor accordingly. For example, a 3.5° slope uses 350ft, 2.5° slope uses 250ft, etc. *Different approach plates display precise figures for the corresponding approach, this ROT is not exact but is a simple method to verify
Estimating distance to touchdown on a 3° glideslope
Distance to touchdown = Height above ground level (AGL) ÷ 300ft
Using the 1 in 60 rule, we can approximate the distance to touchdown. Example: We are fully established on a 3° ILS at an indicated altitude of 1607ft. If we have a radio altimeter or set our altimeter to QFE, we can obtain the height above ground immediately. If not, we have to subtract runway elevation from altitude. The runway has a touchdown zone elevation of 707ft. Therefore, our height above ground is 1607 - 707 = 900ft. Distance to touchdown = 900ft/300ft = 3NM *For other angles, adjust the 300ft factor accordingly. For example, a 3.5° slope uses 350ft, 2.5° slope uses 250ft, etc. *Please note that this ROT is for HEIGHT above aerodrome level!