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Aircraft Speed

Introduction:

  • Same as you have speed limits on the road, they exist in the sky
  • Their purposes is to facilitate the most safe and efficient flow of traffic, especially in the low altitude and terminal structure

Civil:

  • Unless otherwise authorized by the administrator, no person may operate an aircraft below 10,000' MSL at an indicated airspeed of more than 250 knots (288 mph)
  • Unless otherwise authorized by ATC, no person may operate an aircraft at or below 2,500' MSL within 4 NM of the primary airport of class C or D airspace at an indicated airspeed of more than 200 knots (230 mph)
  • No person may operate an aircraft in the airspace underlying a class B airspace area designated for an airport or in a VFR corridor designated through such a class B airspace area, at an indicated airspeed of more than 200 knots (230 mph)
    • However, inside of class B aircraft below 10,000' MSL are authorized to fly in excess of 200 knots but no more than 250 knots
  • If the minimum safe airspeed for any particular operation is greater than the maximum prescribed speed, the aircraft may be operated at that minimum speed

Speed Adjustments:

  • ATC will issue speed adjustments to pilots of radar-controlled aircraft to achieve or maintain required or desired spacing
  • ATC will express all speed adjustments in terms of knots based on indicated airspeed (IAS) in 10 knot increments except that at or above FL240 speeds may be expressed in terms of Mach numbers in 0.01 increments
  • The use of Mach numbers is restricted to turbojet aircraft with Machmeters
  • Speeds will be assigned in accordance with the following minimums:
    • To aircraft operating between 10,000' and FL280 a speed not less than 250 knots or the equivalent Mach number
    • On a standard day in Mach numbers equivalent to 250 knots CAS (subject to deviation):
      • FL240: 0.60
      • FL250: 0.61
      • FL260: 0.62
      • FL270: 0.64
      • FL280: 0.65
      • FL290: 0.66
    • When an operational advantage will be realized, speed lower than the recommended minima may be applied
  • To arriving turbo jet aircraft operating below 10,000'
    • A speed not less than 210 knots, except within 20 flying miles of the airport of intended landing, a speed not less than 170 knots
  • To arriving reciprocating engine or turbo-prop aircraft within 20 flying miles of the runway threshold of the airport of intended landing, a speed not less than 150 knots
  • To departing aircraft:
    • Turbojet aircraft, a speed not less than 230 knots
    • Reciprocating engine aircraft, a speed not less than 150 knots
  • When ATC combines a speed adjustment with a descent clearance, the sequence of delivery, with the word "then" between, indicates the expected order of execution
    • ATC: "Descend and maintain [altitude]; then, reduce speed to [speed]"
    • ATC: "Reduce speed to [speed]; then, descend and maintain [altitude]"
  • Approach clearances supersede any prior speed adjustments, and pilots are expected to make their own speed adjustments, as necessary to complete the approach
  • Under certain circumstances, however, it may be necessary for ATC to issue further speed adjustments after approach clearance is issued to maintain separation between successive arrivals
    • Under such circumstances, previously issued speed adjustments will be restated if that speed is to be maintained or additional speed adjustments are requested
    • ATC must obtain pilot concurrence for speed adjustments after approach clearances are issued
    • Speed adjustments should not be assigned inside the FAF on final or a point 5 miles from the runway, whichever is closer to the runway
      • "Resume normal speed" does not delete speed restrictions that are contained in a published procedure unless specified
  • The pilots retain the prerogative of rejecting the application of speed adjustment by ATC if the minimum safe airspeed for any particular operation is greater than the sped adjustment
  • Pilots are reminded that they are responsible for rejecting the application of speed adjustments by ATC if, in their opinion, it will cause them to exceed the maximum indicated airspeed prescribed by 91.117(a),(c) and (d)
    • Inform ATC if unable to comply
  • Pilots operating at or above 10,000' MSL who are issued speed adjustments which exceed 250 knots IAS and are subsequently cleared below 10,000' MSL are expected to comply with FAR 91.117(a)
  • Speed restrictions of 250 knots do not apply to U.S. Registered aircraft operating beyond 12 nm from the coastline within the U.S. Flight Information Region, in Class E airspace below 10,000' MSL
    • However, in airspace underlying a Class B airspace area, pilots are expected to comply with the 200 knot speed limit in FAR 91.117(c) 200 KIAS (230 MPH)
  • For operations in a Class C and Class D surface area, ATC is authorized to request or approve a speed greater than the maximum indicated airspeeds prescribed for operation within that airspace in FAR 91.117(b) 200 KIAS (230 MPH)
  • When communications with ARTCC or approach control facility, pilots should, as a good operating practice, state any ATC assigned speed restriction on initial radio contact associated with an ATC communications frequency change
  • Pilot:
    • Advises ATC any time cruising airspeed varies plus or minus 5% or 10 knots, whichever is greater from that given in the flight plan
    • When complying with speed adjustments, maintain an IAS within 10 knots or 0.02 Mach
  • Controller:
    • Assigns speed adjustments
    • Avoids alternating increase and decreasing airspeeds
    • Does not assign speed adjustments to aircraft at or above FL390 without pilot consent
    • Advises pilots to resume normal speed when speeds adjustments are no longer required

Supersonic Flight Operations:

  • Commanding officers assigned aircraft capable of supersonic flight shall ensure that aircrews are thoroughly familiar with the shock wave phenomenon peculiar to supersonic flight. Serious damage, annoyance, and mental stress have resulted from sonic booms. It is incumbent on every pilot flying aircraft capable of generating sonic booms to reduce such disturbances and damage to the absolute minimum dictated by operational/training requirements

  • Policy:
    • Supersonic flight operations shall be strictly controlled and supervised by operational commanders. Supersonic flight over land or within 30 miles offshore shall be conducted in specifically designated areas. Such areas must be chosen to ensure minimum possibility of disturbance. As a general policy, sonic booms shall not be intentionally generated below 30,000' of altitude unless over water and more than 30 miles from inhabited land areas or islands. Deviations from the foregoing general policy may be authorized only under one of the following:
      • Tactical missions that require supersonic speeds
      • Phases of formal training syllabus flights requiring supersonic speeds
      • Research, test, and operational suitability test flights requiring supersonic speeds
      • When specifically authorized by CNO for flight demonstration purposes
  • Reports, Inquiries, and Investigations:
    • The Department of the Navy must accept responsibility for restitution and payment of just claims for damage resulting from sonic booms determined to have been caused by naval aircraft
    • To assist in determining validity of claims, all supersonic flights conducted over the CONUS or within 50 miles offshore shall be logged as to time, date, location, speed, and altitude of occurrence and retained at the unit level for 24 months
    • Section 0910f of reference (r) provides information and instructions concerning investigations into sonic boom complaints and alleged damage claims

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