Speed management during arrivals is one of those topics that sounds simple until you realize there are at least three separate layers of rules that can all apply at once: a regulatory ceiling baked into 14 CFR, speed restrictions printed right on the chart, and real-time ATC instructions. Miss any layer and you could bust a limit, overload ATC's sequencing plan, or — in the worst case — close in on traffic ahead faster than you can react. For instrument pilots, getting this right starts on the ground, in ground school, and gets refined in the cockpit on every arrival.
This article walks through each layer in detail: where the rules come from, how they interact, when ATC can modify them, and how to read charted speed restrictions correctly. You will also find the specific numbers the FAA knowledge test loves to probe, common traps students fall into, and the practical cockpit discipline that keeps professional pilots out of trouble.
The Regulatory Foundation: 14 CFR 91.117
The primary speed regulation for arrivals is 14 CFR 91.117, which establishes speed limits that apply to all aircraft operating in U.S. airspace regardless of whether they are IFR or VFR. Understanding the exact language of this rule is essential because the knowledge test often exploits its nuances.
Below 10,000 feet MSL: No person may operate an aircraft at an indicated airspeed of more than 250 knots. This applies everywhere below 10,000 feet MSL in the contiguous United States — not just in terminal areas. The altitude reference is MSL, not AGL, which matters at airports in mountainous terrain where the surface itself may be several thousand feet above sea level.
At or below 2,500 feet AGL within 4 nautical miles of the primary airport of a Class C or Class D airspace: The limit drops to 200 knots indicated. This is one of the most-tested distinctions. Note carefully: the 200-knot limit is referenced to AGL, while the 250-knot limit is referenced to MSL. The 4-nautical-mile radius is measured from the primary airport, not from any surrounding Class C shelf boundary.
Within a Class B airspace VFR corridor designated for that purpose: The same 200-knot limit applies to all aircraft operating within that corridor. However, within Class B airspace itself, the general rule allows ATC to issue speeds appropriate for the environment, often higher, as long as the aircraft remains below 250 knots below 10,000 feet MSL.
One important exception: if the minimum safe airspeed for any particular aircraft is greater than the specified limit, that aircraft may be operated at that minimum safe airspeed. This exception does not give pilots wide discretion — it applies to situations such as a large, heavily loaded aircraft where flying at 200 knots would compromise safe flight, and ATC must typically be informed.
Charted Speed Restrictions on STARs
Standard Terminal Arrival Routes (STARs) are published procedures designed to transition aircraft from the enroute structure to the approach environment efficiently. To enable ATC to sequence multiple aircraft onto a single arrival fix or runway without issuing individual speed assignments to every flight, STARs frequently carry published speed restrictions right on the chart itself.
These restrictions appear in two forms:
- Maximum speed restrictions: Published as a speed value with an overbar or the notation "AT OR BELOW [speed] KTS." They cap how fast you may be going at or before that fix.
- Mandatory speed restrictions: Published with both an overbar and an underbar, or the notation "AT [speed] KTS," meaning you must cross that fix at exactly that speed — not above, not below.
- Minimum speed restrictions: Less common, but published with an underbar notation meaning "AT OR ABOVE [speed] KTS" at that fix. These may appear where spacing from slower traffic must be maintained.
Just like altitude restrictions on STARs, speed restrictions on a STAR procedure are mandatory unless ATC explicitly cancels or modifies them. If you are cleared for the STAR, you are expected to comply with every speed and altitude constraint on that procedure. A clearance that says "Cleared STAR, descend via" includes the obligation to meet every constraint. If ATC says "descend and maintain FL240" without saying "descend via," that altitude assignment supersedes the STAR altitude constraints, but speed constraints may still apply unless separately amended.
On some STARs you will see a note at the top of the chart such as "TURBOJETS EXPECT PILOT NAV AFTER [fix]" or speed planning notes directed at specific aircraft categories. Read the chart notes carefully — they are part of the published procedure and carry operational weight.
ATC Speed Assignments
Beyond the regulatory minimums and charted restrictions, ATC has authority to issue speed assignments — specific speeds or speed ranges that you are expected to achieve and maintain. These are issued for separation, sequencing, and runway throughput. Under 14 CFR 91.123, a pilot operating under IFR in controlled airspace must comply with ATC clearances and instructions, which includes speed assignments unless compliance would compromise safety.
When ATC assigns a speed, it supersedes any published STAR speed restriction for that segment, but it does not cancel the regulatory 250-knot limit below 10,000 feet or any other regulatory floor. ATC cannot legally authorize you to exceed 250 knots below 10,000 feet MSL — they simply do not have that authority under Part 91. If a controller issues an assignment that would require you to bust a regulatory limit, you must comply with the regulation and advise the controller.
ATC often uses the phrasing "reduce speed to [X] knots", "maintain [X] knots", or "increase speed to [X] knots." Once you pass the segment or fix for which the speed was assigned, you should revert to published constraints or request clarification unless the controller tells you to maintain that speed. A common misunderstanding is treating an ATC speed assignment as applying to the entire remainder of the arrival — it does not unless explicitly stated.
Why Speed Control Matters in the Terminal Environment
The arrival environment compresses time and space rapidly. Aircraft on a STAR may be separated by only a few miles in trail, descending through changing winds, decelerating through multiple constraints, and managing complex aircraft configurations — all while monitoring multiple radio frequencies. A speed bust of even 20–30 knots can collapse the separation between you and the aircraft ahead in a matter of minutes.
Published speed constraints also protect obstacle clearance on some procedures. While the primary purpose of STAR speed restrictions is sequencing, some fixes with step-down constraints rely on the aircraft being within a certain speed-altitude envelope to ensure the aircraft can make the subsequent altitude restriction. Flying too fast through a constraint fix can result in being too high for the next fix with no legal way to descend fast enough.
Speed control also ties directly into fuel management and aircraft configuration. Arriving too fast forces a rushed configuration, which can lead to unstabilized approaches — one of the leading causal factors in approach-and-landing accidents. Many airline standard operating procedures call for a go-around if the aircraft is not stabilized by a specific gate altitude, and that discipline starts with professional speed management miles before the final approach fix.
Key Numbers and Rules
- 250 KIAS: Maximum speed below 10,000 feet MSL — applies everywhere, all airspace classes, IFR and VFR. Reference altitude is MSL.
- 200 KIAS: Maximum speed at or below 2,500 feet AGL within 4 NM of the primary airport of a Class C or Class D airspace surface area. Reference altitude is AGL.
- 4 nautical miles: The radius measured from the primary airport (not a boundary) that triggers the 200-knot limit.
- Charted STAR speed restrictions are mandatory unless amended by ATC; a "descend via" clearance includes all speed and altitude constraints.
- ATC speed assignments supersede charted restrictions for that segment but cannot authorize exceedance of regulatory speed limits.
- Minimum safe airspeed exception: An aircraft may exceed a 14 CFR 91.117 speed limit if minimum safe airspeed for that aircraft is higher, but ATC must be informed.
Memory Aid
"Ten and Two-Fifty; Four and Two-Hundred" — This phrase captures the two key speed limits: at 10,000 feet MSL the limit is 250 knots; within 4 nautical miles of Class C or D primary airports at or below 2,500 feet AGL the limit drops to 200 knots. Pair this with the altitude reference switch: 10,000 is MSL, 2,500 is AGL — the references are different, and that difference is exactly what the test will exploit.
Common Test Traps
- MSL vs. AGL confusion: The 250-knot limit is triggered at 10,000 feet MSL, but the 200-knot limit is triggered at 2,500 feet AGL. Students routinely mix these up. A mountain airport at 5,500 feet MSL means the 200-knot zone doesn't begin until 8,000 feet MSL (2,500 feet AGL above the surface).
- Assuming "Descend and Maintain" cancels speed restrictions: An altitude-only instruction does not cancel charted STAR speed restrictions. Only an explicit ATC speed amendment or cancellation of the STAR itself removes the speed obligation.
- Treating ATC speed assignments as permanent: An ATC speed assignment applies to the segment for which it is issued. Once past that fix or segment, revert to published constraints or the regulatory default unless otherwise instructed.
- Forgetting the 200-knot rule applies to Class C, not just Class D: Both Class C and Class D surface areas trigger the 200-knot limit within 4 NM. Students sometimes believe only Class D or only Class B triggers it.
- Thinking Class B airspace itself imposes a 250-knot restriction: The 250-knot limit below 10,000 feet MSL is a regulatory floor everywhere, not a special Class B rule. The unique Class B provision in 91.117 addresses the VFR corridor and certain prop-driven aircraft categories, not the general 250-knot rule, which already applies by default.