Auto flight/navigation (descent) Flashcards
What is the 3:1 descent ratio used for?
It is used to plan and execute an idle descent, losing approximately 1,000 feet every 3 miles.
What is the basic equation for calculating distance required for descent using the 3:1 ratio?
(altitude to lose/1,000) x 3 = distance required
What is the difference between an idle-path and a geometric-path descent profile?
idle-path descent = idle thrust
geometric path descent = straight line descent from one waypoint to the next.
At what speed does the IAS/MACH speed window change from MACH to IAS during descent?
Approximately 300 KIAS.
What type of altitude constraint cannot be entered manually?
A block altitude.
When is a block altitude displayed?
When contained within an FMC procedure (i.e., SID, STAR, or approach) selected from the navigation database.
What should be done if a block altitude is inadvertently deleted?
Reselect the FMC procedure.
How are ‘At or above’ airspeed restrictions entered on the Legs page?
With a suffix letter A (example: 250A)
How are ‘At or below’ airspeed restrictions entered on the Legs page?
With a suffix letter B (example: 200B)
How are mandatory airspeed restrictions entered on the Legs page?
Without any suffix letter (example: 220)
How are ‘At or above’ altitude restrictions entered on the Legs page?
With a suffix letter A (example: 220A)
How are ‘At or below’ altitude restrictions entered on the Legs page?
With a suffix letter B (example: 240B)
How are mandatory altitude restrictions entered on the Legs page?
Without any suffix letter (example: 270)
How is the top-of-descent (TOD) depicted on the ND?
As a green open circle with the label T/D
What FMS scratchpad message is received within 5 NM of the TOD if a lower MCP altitude has not been selected?
‘RESET MCP ALTITUDE’ message appears on the FMS scratchpad
What pitch mode does the FMA display if the TOD point is reached without a lower altitude set in the MCP?
Changes from VNAV PTH to ALT HOLD
What is the most economical descent method?
An FMS path descent
What is the preferred method for descent within 50 miles from TOD?
Entering a lower altitude in the MCP, selecting, and executing the DES NOW prompt
What does the V/S pitch mode do?
Commands pitch guidance to maintain selected vertical speed
