Task IV.L
Rough Water Approach and Landing (ASES, AMES)
To determine the applicant exhibits satisfactory knowledge, risk management, and skills associated with rough water approach and landing.
Note: If a rough water condition does not exist, the applicant must be evaluated by simulating the Task.
References: AIM; FAA-H-8083-2, FAA-H-8083-3, FAA-H-8083-23, FAA-H-8083-25; POH/AFM
Quick Review
Conversational Q&A — quiz yourself before the oral. This Task applies to ASES and AMES applicants only. If a rough water condition does not exist, you will be evaluated by simulating the Task (ACS Task IV.L note).
Maintain the manufacturer's published approach airspeed, or in its absence not more than 1.3 VSO, ±5 knots with the gust factor applied (CA.IV.L.S7) — tightened from +10/−5 at private.
There is no touchdown distance box on this Task. What is graded instead: contact the water in a proper pitch attitude, considering the type of rough water (CA.IV.L.S10). Maintain directional control and crosswind correction throughout (CA.IV.L.S8).
Because the handbook says describing a typical or ideal one is impractical, given the many variables that affect the water's surface — wind direction and speed have to be weighed together with the surface conditions (FAA-H-8083-23 ch. 6). "Rough" is also relative: water that causes a large seaplane or an experienced pilot no difficulty may be very dangerous for a smaller seaplane or a less experienced pilot. Judgment is the maneuver.
In most instances, make the approach the same as for any other water landing. Then (FAA-H-8083-23 ch. 6):
- It may be better to level off just above the water and add enough power to maintain a rather flat attitude until conditions appear more acceptable, then reduce power to touch down.
- Touch down at a somewhat flatter pitch attitude than usual. This prevents the seaplane from being tossed back into the air at a dangerously low airspeed, and lets the floats slice through the tops of the waves rather than slamming against them.
- Reduce power as the seaplane settles into the water.
- Apply back pressure as it comes off the step to keep the float bows from digging into a wave face.
Two triggers call for abandoning the landing (FAA-H-8083-23 ch. 6). Severe bounces: add power and lift off to search for a smoother landing spot. A large wave throwing the seaplane airborne before it comes off the step: be ready to apply full power and go around.
Both are pre-briefed decisions, not improvisations — you should be flying the approach with a hand on the throttle and a go-around already decided in principle.
A downwind landing means wind velocity adds to the normal landing speed, producing a much higher groundspeed — because rough water is usually an indication of strong wind, and vice versa. That higher groundspeed:
- imposes excessive stress on the floats
- increases the nose-down tendency at touchdown
- prolongs the water run, since more kinetic energy must be dissipated
As the seaplane slows, the tendency to weathervane may combine with the rough surface motion to create an unstable situation (FAA-H-8083-23 ch. 6). Upwind gives a much lower touchdown speed, a shorter water run, and far less pounding.
Avoid it. Crosswind landings on rough water or in strong winds leave the seaplane vulnerable to capsizing — the pitching and rolling produced by the water motion increases the likelihood of the wind lifting a wing and flipping the seaplane (FAA-H-8083-23 ch. 6). Keep in mind the allowable crosswind component for a floatplane may be significantly less than for the equivalent landplane (FAA-H-8083-23 ch. 4).
Skipping is a cyclic vertical oscillation from touching the water at excessive speed with too high a pitch angle — it can also be triggered by crossing a wake. It feels like vertical G, whereas porpoising feels like a fore-and-aft rocking chair.
Correct it by increasing back pressure and adding sufficient power to prevent the floats from contacting the water, then establishing the proper pitch attitude and reducing power gradually to let the seaplane settle gently. Skipping does not grow in amplitude the way porpoising does, but it pounds the floats and airframe and can lead to porpoising (FAA-H-8083-23 ch. 4).
Options. Establish the recommended configuration, airspeed, and trim, adjusting pitch and power to maintain a stabilized approach (CA.IV.L.S6). You arrive with a known energy state — which is what lets you level off, hold a flat attitude with power while you evaluate the surface, and either accept the water or leave. An unstable approach to rough water gives you a single arrival with no look-and-decide segment. That is the energy-management point the ACS is after.
Official ACS elementsreference
Knowledge5 elements
The applicant demonstrates understanding of:
CA.IV.L.K1A stabilized approach, including energy management concepts.CA.IV.L.K2Effects of atmospheric conditions, including wind, on approach and landing performance.CA.IV.L.K3Wind correction techniques on approach and landing.CA.IV.L.K4When and why rough water techniques are used.CA.IV.L.K5How to perform a proper rough water approach and landing.
Risk Management12 elements
The applicant is able to identify, assess, and mitigate risk associated with:
CA.IV.L.R1Selection of approach path and touchdown area based on pilot capability, airplane performance and limitations, available distance, and wind.CA.IV.L.R2Effects of:CA.IV.L.R2aCrosswindCA.IV.L.R2bWindshearCA.IV.L.R2cTailwindCA.IV.L.R2dWake turbulenceCA.IV.L.R2eWater surface/conditionCA.IV.L.R3Planning for a go-around and rejected landing.CA.IV.L.R4Collision hazards.CA.IV.L.R5Low altitude maneuvering, including stall, spin, or controlled flight into terrain (CFIT).CA.IV.L.R6Distractions, task prioritization, loss of situational awareness, or disorientation.CA.IV.L.R7Gear position in an amphibious airplane.
Skills10 elements
The applicant exhibits the skill to:
CA.IV.L.S1Complete the appropriate checklist(s).CA.IV.L.S2Make radio calls as appropriate.CA.IV.L.S3Ensure the airplane is aligned with the correct/assigned waterway.CA.IV.L.S4Scan the landing area for traffic and obstructions.CA.IV.L.S5Select and aim for a suitable touchdown point considering the wind conditions, landing surface, and obstructions.CA.IV.L.S6Establish the recommended approach and landing configuration, airspeed, and trim, and adjust pitch attitude and power as required to maintain a stabilized approach.CA.IV.L.S7Maintain manufacturer’s published approach airspeed or in its absence not more than 1.3 times the stalling speed or the minimum steady flight speed in the landing configuration (VSO), ±5 knots with gust factor applied.CA.IV.L.S8Maintain directional control and appropriate crosswind correction throughout the approach and landing.CA.IV.L.S9Make smooth, timely, and correct power and control adjustments to maintain proper pitch attitude and rate of descent to touchdown.CA.IV.L.S10Contact the water in a proper pitch attitude, considering the type of rough water.