Ninety-One One Seventeen, the Speed Limit Nobody Reads Until Ninety Knots on the Fisk Arrival Makes It Personal

Federal aviation regulation 14 CFR 91.117 sets the maximum speeds you may fly at low altitude: 250 knots indicated airspeed below 10,000 feet MSL, and 200 knots when you’re low and close to a towered airport or beneath Class B airspace. These are ceilings, not targets - which is exactly why the 90-knot Oshkosh arrival procedure can legally require you to fly far slower than the reg allows. Understanding how a maximum-speed rule and a special-event procedure fit together is the difference between reciting a regulation and actually flying it.

What Does 14 CFR 91.117 Actually Say?

The regulation is short - just four paragraphs - but pilots get it wrong constantly because it sounds simpler than it is. Here it is in plain English.

Paragraph (a): Below 10,000 feet MSL, you may not operate an aircraft faster than 250 knots indicated airspeed. This is the one everybody half-remembers.

Paragraph (b): At or below 2,500 feet above ground level (AGL), and within 4 nautical miles of the primary airport of a Class C or Class D airspace area, you may not exceed 200 knots - unless ATC authorizes otherwise. All three conditions must be true at once.

Paragraph (c): In the airspace underlying Class B, or in a VFR corridor through Class B, the limit is 200 knots.

Paragraph (d): If the minimum safe airspeed for a particular operation is greater than the maximum in the rule, you may fly that minimum safe speed instead. The regulation will never force you to fly dangerously slow.

Why Is the Speed Limit 250 Knots Below 10,000 Feet?

The 10,000-foot line isn’t arbitrary. Below that altitude is where the traffic lives - general aviation aircraft, training flights, and airliners climbing out and descending in. It’s the crowded floor of the sky.

Consider the math. Two aircraft head-on, each doing 250 knots, produce a closure rate of 500 knots - roughly 8 nautical miles per minute coming together. That gives you very little time to see and react. Now imagine no limit at all, with one aircraft doing 400 knots.

The entire purpose of the rule is to keep closure speeds inside the envelope of what a human’s eyes and brain can actually handle.

For most pilots flying a Cessna 172 or a Piper, paragraph (a) is academic - your trainer won’t hit 250 knots in a dive. But it matters the day you move up to a fast experimental, a turbine, or anything that can actually run. Examiners want you to know the number and know why it exists.

What’s the Difference Between the 200-Knot Rules?

This is where pilots trip up, because paragraph (b) has three conditions that must all be met simultaneously:

• At or below 2,500 feet AGL
• Within 4 nautical miles
• Of the primary airport of a Class C or D

Notice what the rule does not say. If you’re near a Class Delta but above 2,500 feet AGL, the 200-knot limit doesn’t apply (though the 250-knot limit still does if you’re below 10,000). And the restriction is a 4-nautical-mile cylinder, not the lateral boundaries of the airspace on your chart. That speed cylinder doesn’t perfectly match the shape of the Class Delta - a common mix-up.

Paragraph (c) is the one that keeps you honest when you’re scooting beneath the shelf of a big Class Bravo, threading below the airliners: underneath the Bravo, 200 knots.

Why Does the Oshkosh Arrival Require Only 90 Knots?

During AirVenture, Wittman Regional Airport is the busiest airport on the planet. The arrival everyone flies runs down the railroad tracks from Ripon, Wisconsin, to Fisk: a single-file line of aircraft holding 90 knots at 1,800 feet MSL, half a mile in trail. Aircraft that can’t safely fly that slow use a higher, faster track at 135 knots and 2,300 feet MSL.

That procedure is published in the AirVenture NOTAM (Notice to Air Missions), a document the FAA and EAA release every year that every arriving pilot is legally required to have read.

So the NOTAM says 90 knots while the regulation says 200 or 250. Who wins? The NOTAM wins.

Here’s why that isn’t a contradiction. 14 CFR 91.117 sets a ceiling - a maximum - and never says you can’t go slower. A NOTAM establishing a procedure for a special event carries the force of a rule you must comply with. The regulation is the fence around the entire field; the NOTAM tells you the exact spot to stand. One gives the outer limit, the other gives the specific number for this specific piece of sky this week.

The reasoning behind 90 knots is the same logic that built 91.117, turned all the way up. When hundreds of aircraft funnel down a set of tracks half a mile apart, the only way it works is if everyone flies the same speed. If you’re doing 90 and the aircraft behind you is doing 120, you have a problem within about 90 seconds. The whole ballet depends on speed discipline.

How Do I Fly the 90-Knot Arrival Correctly?

Picture yourself inbound to Ripon in a Cherokee. You slot into the line at 1,800 feet, glance at your airspeed indicator, and you’re doing 110 knots because your hand crept the throttle forward. The aircraft ahead - doing it right at 90 - is filling your windshield fast. Here’s how to handle it:

1. Don’t yank the power or balloon up. Sudden pitch changes disrupt everyone behind you.
2. Smoothly reduce power and let the aircraft settle back to 90 knots.
3. If you’re still overtaking, break off, climb, and re-enter the line rather than crowd the aircraft ahead - exactly as the NOTAM directs.

Fly the speed precisely, the way you’d fly a short final. This is where all those hours of slow flight and airspeed control pay off - holding a target airspeed within a few knots while your attention is split across traffic, radios, and terrain.

Why Does Airspeed Control Matter So Much?

Speed control is a fundamental piloting skill that pilots undervalue because it feels boring. Anybody can push the throttle up. But holding a precise airspeed - in the pattern, on an approach, in a crowded arrival - while your attention is divided is real airmanship.

The Airman Certification Standards (ACS) spell out airspeed tolerances for exactly this reason. On a normal approach, the standard expects you within a handful of knots of your target. That precision keeps you predictable, and predictability is what keeps everyone safe when the sky gets crowded.

And it doesn’t take Oshkosh. Every busy Saturday at your home field is a small version of the same thing: a fast experimental on downwind, a student in a Cessna 152 on final, a twin in the run-up. It works because everyone is flying compatible pattern speeds. 91.117 is the legal floor under that; good airmanship is the rest.

Key Takeaways

• Know the numbers cold: 250 knots below 10,000 feet MSL; 200 knots at or below 2,500 AGL within 4 NM of a Class C or D primary airport; 200 knots beneath Class B - and you’re never required to fly unsafely slow.
• These are ceilings, not targets. The regulation tells you the fastest you may go; NOTAMs, procedures, and judgment routinely tell you to go slower, and when they do, they win.
• The reg and the NOTAM don’t conflict. 14 CFR 91.117 draws the outer fence; the AirVenture NOTAM tells you the exact spot to stand at 90 knots.
• The 4-NM speed restriction near Class C/D is a cylinder, not the charted airspace boundary - and it only applies at or below 2,500 feet AGL.
• Treat airspeed control as a core skill. The pilot who nails 90 knots down the tracks at Fisk is the same pilot who nails a gusty crosswind approach.