Many passengers experience take-off as a familiar sequence: the engines roar to life, the aircraft accelerates down the runway, takes off, and climbs steeply. However, it is often just as noticeable when the aircraft suddenly levels off while still at a relatively low altitude. In the United States, a common interim level-off is at 10,000 feet (3,050 meters), although this varies by airport, air traffic conditions, and other circumstances.

Sometimes the interim altitude is different due to terrain, and passengers taking off from Denver will not feel the change at 10,000 feet. The Federal Aviation Administration ( FAA) only has jurisdiction over United States airspace and select delegated areas of international airspace. Other regions use their own air traffic management systems within the broader framework of International Civil Aviation Organization (ICAO) standards.

Descent involves a similar but different set of procedures, with air traffic controllers managing both altitude and speed as aircraft are sequenced for landing. Let’s examine the FAA phraseology rules behind the interim climb and descent transitions that many passengers feel.

Leveling Off At 10,000 Feet

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After takeoff, commercial aircraft often climb through 10,000 feet. Commonly, on some busy departures air traffic control temporarily levels the aircraft at that altitude. At this point, passengers notice a brief pause in the climb as the aircraft levels off. This is the part of the flight soon after takeoff that passengers often feel as the engines reduce thrust. The aircraft transitions to level flight even though it is far below its cruise altitude.

On a busy departure, air traffic control may clear the aircraft to climb and maintain 10,000 feet, creating a temporary level-off while the crew awaits a further climb clearance. Once air traffic control clears the aircraft higher, for example “climb and maintain flight level 350“—the climb resumes. Alternatively, the aircraft may be cleared to “climb via SID“, allowing it to follow the published departure’s altitude and speed restrictions.

The level off is easy for passengers to notice as the noise lowers slightly and the sensation of being pushed back in the seats decreases. The engines often become quieter as the aircraft normally accelerates after passing 10,000 feet and transitions from climb thrust (or flap-related procedures) to higher-speed climb configurations.

Not An FAA Requirement

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The key FAA phraseology rule is “Maintain one zero thousand.” “Maintain,” in this context, means that the aircraft is to remain at the assigned altitude until receiving a new clearance. Thus, an instruction to “climb and maintain 10,000” requires the aircraft to climb to 10,000 feet and then level off there.

One important distinction to make is between this and “climb via SID.” The latter instructs the aircraft to follow the SID’s published lateral, altitude, and speed restrictions while climbing, rather than simply climbing to a single assigned altitude. An airliner that is cleared to “climb via SID” may pass through 10,000 feet without leveling off, although the SID or a subsequent air traffic control instruction can still impose an altitude restriction there. The familiar 10,000-foot pause is not a universal FAA requirement, and it is often not used in airports with less air traffic or in challenging terrain (discussed below).

The pause at this altitude is the result of a particular air traffic control clearance being used to manage traffic, combined with the aircraft’s normal changes in thrust, speed, and configuration during the climb. While it’s not possible to explain here, the development of FAA phraseology has been a long and scientific process to provide the most clarity and the least confusion for pilots from multiple native-language backgrounds.

Why ATC Uses 10,000 Feet

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Air traffic control commonly uses 10,000 feet as it provides a practical coordination altitude, allowing the separation of departing and arriving traffic around busy terminal airspace. It also provides a predictable handoff between the terminal and en-route controls and gives air traffic control flexibility to sequence aircraft before clearing them to fly higher.

The widespread use of 10,000 feet is mostly an operational convention within the FAA’s terminal airspace system. The altitude is not because that level has particular relevance to aircraft performance. The altitude has the advantage of sitting between the busiest low-altitude arrival and departure flows and the high-altitude of aircraft en route. Put another way, it is an ideal midway altitude for sequencing air traffic.

Another factor is that the US 250-knot speed limit generally applies below 10,000 feet, so aircraft can accelerate after passing it. While altitude is very commonly used in the United States, it is not ubiquitous. Low-density airports often clear departing aircraft to directly climb to a much higher altitude. In Europe, air traffic control generally uses multiple interim altitudes, such as FL150, FL190, and FL240.

Taking Off Over Mountains & Oceans

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The presence of mountains and oceans also has a significant impact on the use of 10,000 feet as an interim altitude. Airports surrounded by high terrain typically have much higher intermediate altitudes. One of the best examples in the United States is Denver, which typically uses 13,000-17,000 feet (3,960-5,180 meters). The airport is already located at an altitude of 5,434 feet (1,565 meters) above sea level. Salt Lake City is another example of a major US airport that frequently uses a different interim altitude.

In more extreme environments, such as aircraft taking off from Bhutan’s Paro International Airport and Pakistan’s northern Skardu Airport in the disputed mountainous region with India, leveling off at 10,000 feet would involve colliding with mountains. Simple Flying has already reported first-hand accounts of flying in and out of these airports, including the hair-pin 180-degree turns pilots have to make in the valleys and the narrow clearances over mountain ridges.

At Tibet’s Lhasa Gonggar Airport, 10,000 feet is below the airport: it already sits at 11,710 feet (3,570 meters). The other major environment where the 10,000 feet interim convention is often not used is oceanic departures (such as Anchorage and Honolulu). Departing flights from those airports are often cleared almost continuously into en-route altitudes after leaving the terminal area. There is relatively little conflicting traffic at an airport like Anchorage.

10,000 Feet During Descent

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Something similar, but still different, happens in descent. The FAA controller guidance explicitly calls simultaneous speed reduction and descent “extremely difficult, particularly for turbojet aircraft.” A descending aircraft naturally wants to accelerate, while slowing down often requires reduced descent rate and added drag. Air traffic controllers are trained to sequence instructions.

With descending aircraft, standard phraseology becomes “reduce speed to 210 knots, then descend and maintain 4,000” or “Descend and maintain 5,000, then reduce speed to 180 knots.” This allows for one energy change at a time. Many passengers notice a long and almost flat segment before final descent. This is the point at which the aircraft has stopped descending and is maintaining the 250-knot speed limit while sequencing with other air traffic.

After spacing becomes available, air traffic control clears a lower altitude, and the aircraft can resume its descent. Air traffic control typically keeps aircraft flying as fast as possible, as airliners operate less efficiently when flying slowly. If an aircraft slows down early, then pilots need to extend flaps or speed brakes, which increases drag and fuel burn.

No Speed Adjustments On Final Approach

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Once an aircraft is inside the final approach fix on final, or within five nautical miles of the runway, whichever is closer to the runway, air traffic control should no longer assign speed adjustments. The reason for this is to protect the stabilized approach. After an aircraft is intercepting the glidepath, pilots are busy with configuring flaps, lowering the landing gear, and maintaining precise vertical and lateral guidance.

Changing speed assignments in this phase would increase an already heavy workload while also interfering with the aircraft’s stability. Importantly, after an approach clearance has been issued, all prior air traffic control speed assignments are automatically canceled unless they are restated. This moves the responsibility for energy management to the pilots.

By this point, a typical narrowbody jet will normally be approaching at roughly 130–150 knots, depending heavily on aircraft type, landing weight, flap configuration, and wind. Larger widebody aircraft occupy a broadly overlapping range, rather than having a completely separate set of landing speeds. Very large aircraft such as the Boeing 747 and Airbus A380 can generally approach at higher speeds, particularly at higher landing weights.

However, their actual approach speeds vary substantially with weight and conditions. The aircraft then slows slightly during the flare before touchdown. There is no single standard touchdown speed: the actual value depends on the aircraft’s approach speed, wind, weight, and landing technique. Just before touchdown, the aircraft enters ground effect caused by the compression of air under its wings and the runway. The airplane pushes through this to touchdown.