violate a succeeding altitude restriction or altitude assignment. 

(See ALTITUDE RESTRICTION.) 

(Refer to AIM.) 

CROSS (FIX) AT OR BELOW (ALTITUDE)- Used by ATC when a maximum crossing altitude at a specific fix is required. It does not prohibit the aircraft from crossing the fix at a lower altitude; however, it must be at or above the minimum IFR altitude. 

(See ALTITUDE RESTRICTION.) 

(See MINIMUM IFR ALTITUDES.) 

(Refer to 14 CFR Part 91.) 

## CROSSWIND- 

a. When used concerning the traffic pattern, the word means “crosswind leg.” 

(See TRAFFIC PATTERN.) 

b. When used concerning wind conditions, the word means a wind not parallel to the runway or the path of an aircraft. 

(See CROSSWIND COMPONENT.) 

CROSSWIND COMPONENT- The wind compo- nent measured in knots at 90 degrees to the longitudinal axis of the runway. 

CRUISE- Used in an ATC clearance to authorize a pilot to conduct flight at any altitude from the minimum IFR altitude up to and including the altitude specified in the clearance. The pilot may level off at any intermediate altitude within this block of airspace. Climb/descent within the block is to be made at the discretion of the pilot. However, once the pilot starts descent and verbally reports leaving an altitude in the block, he/she may not return to that altitude without additional ATC clearance. Further, it is approval for the pilot to proceed to and make an approach at destination airport and can be used in conjunction with: 

a. An airport clearance limit at locations with a standard/special instrument approach procedure. The CFRs require that if an instrument letdown to an airport is necessary, the pilot shall make the letdown in accordance with a standard/special instrument approach procedure for that airport, or 

b. An airport clearance limit at locations that are within/below/outside controlled airspace and with- out a standard/special instrument approach procedure. Such a clearance is NOT AUTHORIZA- 

TION for the pilot to descend under IFR conditions below the applicable minimum IFR altitude nor does it imply that ATC is exercising control over aircraft in Class G airspace; however, it provides a means for the aircraft to proceed to destination airport, descend, and land in accordance with applicable CFRs governing VFR flight operations. Also, this provides search and rescue protection until such time as the IFR flight plan is closed. 

(See INSTRUMENT APPROACH PROCEDURE.) 

CRUISE CLIMB- A climb technique employed by aircraft, usually at a constant power setting, resulting in an increase of altitude as the aircraft weight decreases. 

CRUISING ALTITUDE- An altitude or flight level maintained during en route level flight. This is a constant altitude and should not be confused with a cruise clearance. 

(See ALTITUDE.) 

(See ICAO term CRUISING LEVEL.) 

## CRUISING LEVEL- 

(See CRUISING ALTITUDE.) 

CRUISING LEVEL [ICAO]- A level maintained during a significant portion of a flight. 

CT MESSAGE- An EDCT time generated by the ATCSCC to regulate traffic at arrival airports. Normally, a CT message is automatically transferred from the traffic management system computer to the NAS en route computer and appears as an EDCT. In the event of a communication failure between the traffic management system computer and the NAS, the CT message can be manually entered by the TMC at the en route facility. 

## CTA- 

(See CONTROLLED TIME OF ARRIVAL.) (See ICAO term CONTROL AREA.) 

## CTAF- 

(See COMMON TRAFFIC ADVISORY FREQUENCY.) 

## CTAS- 

(See CENTER TRACON AUTOMATION SYSTEM. ) 

## CTOP- 

(See COLLABORATIVE TRAJECTORY OPTIONS PROGRAM) 

## CTRD- 

(See CERTIFIED TOWER RADAR DISPLAY.) 

