AA.I.H.K4
H
What does AA.I.H.K4 mean?
How to locate and identify seaplane bases on charts or in directories..
- Area of Operation
- I
- Task
- H
- Element type
- A Knowledge element — a fact, concept, or procedure the FAA expects you to know and that the knowledge (written) test draws questions from.
What you need to know
For seaplane operations, you need to evaluate a water surface much like you'd evaluate a runway, but the variables are dynamic: wind direction/strength, current direction/strength, wave height and swell pattern, and hazards like debris, sandbars, shoals, and boat wakes all interact to determine the safest takeoff/landing path and where glassy or rough water technique is needed. Float or hull design affects step location, hydrodynamic lift, and spray patterns, which in turn affects how much water surface (and what conditions) the airplane needs to get on the step and unstick. Porpoising (a pitching oscillation) and skipping (a bouncing motion) are caused by incorrect pitch attitude relative to the step during takeoff or landing — too nose-high or nose-low disturbs the balance of hydrodynamic and aerodynamic forces — and the fix is a prompt, positive pitch correction back to the proper attitude, or aborting if it worsens. You should also know that seaplane bases (land or water) are depicted on charts and in the Chart Supplement/directories with their own symbology, and be able to locate relevant information such as water depth, obstructions, and traffic patterns for a given area.
Why students miss this
Students often treat a water surface like a runway with fixed dimensions, forgetting that wind, current, wakes, and debris can change its usable length and safety in minutes, so they misjudge which factors most affect takeoff and landing planning. They also confuse the causes of porpoising with those of skipping, missing that one relates to pitch oscillation around the step and the other to bouncing on the step itself, which leads to picking the wrong corrective control input.
Focus on: Study the aerodynamic relationship between the float/hull step, pitch attitude, and water contact so you can correctly distinguish porpoising from skipping and name the right corrective response for each.
Drill this area until it sticks
AA.I.H.K4 came from a question you missed on the FAA Airline Transport Pilot Multiengine Airplane knowledge test. Drill ACS-aligned practice questions with AI explanations and the cited FAA handbook reference behind every answer — free to start.
Missing it isn't a verdict on you — it's a sign your prep skipped the why behind it. Memorizing answer letters is exactly what leaves gaps like this. Here, every answer explains the reasoning and cites the FAA source it comes from, so the concept holds on test day and at the checkride oral.
Related ACS codes in H
Other elements the FAA tests under this same Task — review them together.
- AA.I.H.K1The characteristics of a water surface as affected by features, such as
- AA.I.H.K1aSize and location
- AA.I.H.K1bProtected and unprotected areas
- AA.I.H.K1cSurface wind
- AA.I.H.K1dDirection and strength of water current
- AA.I.H.K1eFloating and partially submerged debris
- AA.I.H.K1fSandbars, islands, and shoals
- AA.I.H.K1gVessel traffic and wakes
+ 8 more elements in this Task.
Common question
What's the real difference between porpoising and skipping in a seaplane?
Porpoising is a pitch oscillation where the nose bobs up and down around the step during takeoff or landing, usually from too much or too little back pressure, while skipping is a series of bounces off the step caused by hitting the water at too high a pitch or speed; each requires a different, specific pilot correction rather than the same fix.
What is an FAA ACS code?
The FAA's Airman Certification Standards (ACS) break each certificate into Areas of Operation, Tasks, and specific Knowledge (K), Risk Management (R), and Skill (S) elements. Every knowledge-test question maps to one code like AA.I.H.K4. When you miss a question, your Airman Knowledge Test Report lists its code so you know exactly what to review.
Have a whole list of codes from your report? Paste them all into our free ACS code lookup to see every weak area at once — or browse the aviation glossary for plain-English definitions.