What Is the Speed Limit Below 10,000 Feet MSL Under 14 CFR 91.117?

The 250-Knot Rule: What 14 CFR 91.117 Actually Says

One of the most straightforward regulations you will be tested on during your private pilot oral exam is the speed limit below 10,000 feet MSL. Under 14 CFR 91.117(a), no person may operate an aircraft below 10,000 feet mean sea level at an indicated airspeed of more than 250 knots. That rule applies to virtually every civilian aircraft you will ever fly, with only narrow FAA-authorized exceptions.

Your examiner will expect you to cite this limit quickly and accurately. More importantly, they will probe whether you truly understand what the rule means in practice — because the details matter just as much as the number itself.

Indicated Airspeed, Not True Airspeed or Groundspeed

Here is where many students stumble: the 250-knot limit is based on indicated airspeed, not true airspeed and not groundspeed. This distinction is more significant than it might seem at first. As altitude increases, true airspeed climbs above indicated airspeed due to thinner air. An aircraft cruising at 250 knots indicated near 9,500 feet MSL could have a true airspeed well above that figure — and that is perfectly legal under 91.117, because the regulation is written around what your airspeed indicator actually reads.

Confusing indicated airspeed with true airspeed is one of the most common errors candidates make when answering this question. If your examiner asks which type of airspeed governs the limit, the answer is always indicated airspeed. The FAR/AIM is unambiguous on this point throughout the discussion of aircraft speed in 91.117.

The 200-Knot Limit in Class B, C, and D Airspace

The 250-knot ceiling is not the only speed restriction you need to know. When operating within the Class B airspace surface area, or within 4 nautical miles of the primary airport of a Class C or Class D airspace area at or below 2,500 feet AGL, the limit drops further to 200 knots indicated airspeed. This tighter restriction exists because those environments are dense with traffic — student pilots on their first solos, airliners on approach, and general aviation aircraft all sharing the same congested airspace around busy airports.

Mixing up the 250-knot and 200-knot limits is one of the most reliable ways to lose credibility with a DPE during the oral. The 200-knot rule is not a replacement for the 250-knot rule — it is an additional, more restrictive layer that applies in specific proximity to certain airports. Both limits exist simultaneously, and the more restrictive one always governs when you are in that airspace.

MSL vs. AGL: Why the Reference Altitude Matters

Another trap that catches unprepared candidates involves the altitude reference itself. The 10,000-foot threshold in 91.117(a) is mean sea level, not above ground level. This matters enormously depending on where you are flying. If you are cruising at 10,500 feet MSL over mountainous terrain where the ground sits at 8,000 feet, you are only 2,500 feet AGL — but you are still above the 10,000-foot MSL threshold and therefore free from the 250-knot restriction.

Conversely, imagine flying at 9,800 feet MSL over flat terrain near sea level. You are nearly two miles above the ground, but the 250-knot limit still applies because you have not crossed the 10,000-foot MSL floor. The regulation draws the line at MSL, full stop. Students who conflate MSL with AGL on this question reveal a gap in their regulatory understanding that an examiner will almost certainly pursue further.

It is also worth noting the practical reality: most private pilot training aircraft are nowhere near capable of approaching 250 knots indicated. A Cessna 172 redlines well below 200 knots. But your examiner does not care whether you will ever personally exceed these limits in a trainer — they care whether you understand the rules that govern all operations in the national airspace system. Knowing 91.117 cold signals that you have studied the regulations seriously and are ready to operate as pilot-in-command.

Putting It All Together for Your Checkride

When your DPE asks about speed limits below 10,000 feet MSL, the complete, confident answer covers three things: the 250-knot indicated airspeed limit that applies broadly below 10,000 feet MSL, the 200-knot indicated airspeed limit that applies in Class B surface areas and within 4 nautical miles of Class C and D primary airports below 2,500 feet AGL, and the clarification that both limits are measured in indicated airspeed against an MSL altitude reference. Exceeding either limit — even momentarily — is a regulatory violation under 14 CFR 91.117, regardless of whether any traffic conflict results.

Understanding the logic behind these rules, not just memorizing the numbers, is what separates a prepared candidate from one who is simply hoping for the best. If you want to practice questions like this in a realistic oral exam format, try SimulatedCheckride.com.