Minimum enroute altitude (MEA) is the lowest published altitude between radio fixes which ensures acceptable navigational signal coverage and meets obstacle clearance requirements between those fixes.
Minimum reception altitude (MRA) is the lowest altitude at which an intersection can be determined.
Minimum crossing altitude (MCA) is the lowest altitude at certain fixes at which an aircraft must cross when proceeding in the direction of a higher minimum enroute IFR altitude.
Minimum obstruction clearance altitude (MOCA) is the lowest published altitude in effect between radio fixes on VOR airways, off-airway routes, or route segments which meets obstacle clearance requirements for the entire route segment, and which ensures acceptable navigational signal coverage within 25 SM (22 NM) of a VOR.
Minimum sector altitude (MSA) is the lowest altitude which may be used under emergency conditions which will provide a minimum clearance of 1,000 feet above all obstacles located in an area contained within a 25 NM sector centered on a radio aid to navigation.
The Enroute Low Altitude Charts are valid for use up to, but not including, 18,000 feet MSL. You should become familiar with FAA Legends 33, 34, and 35, which depict the legends for the charts. These will be available to you when you take the FAA Knowledge Test.
Holding may be necessary when ATC is unable to clear a flight to its destination. VORs, nondirectional beacons (NDBs), airway intersections, and DME fixes may all be used as holding points. Flying a holding pattern involves two turns and two straight-and-level legs as shown in Figure 7-1.

Figure 7-1
At and below 14,000 feet MSL (no wind), the aircraft flies the specified course inbound to the fix, turns to the right 180°, flies a parallel course outbound for 1 minute, again turns 180° to the right, and flies 1 minute inbound to the fix. Above 14,000 feet MSL, the inbound leg length is 1-1/2 minutes. If a nonstandard pattern is to be flown, ATC will specify left turns.
When 3 minutes or less from the holding fix, the pilot is expected to start a speed reduction so as to cross the fix at or below the maximum holding airspeed. For all aircraft between minimum holding altitude (MHA) and 6,000 feet MSL, holding speed is 200 KIAS. For all aircraft between 6,001 and 14,000 feet MSL, holding speed is 230 KIAS. For all aircraft 14,001 feet MSL and above, holding speed is 265 KIAS. Exceptions to these speeds will be indicated by an icon.
The aircraft is holding as of the initial time of arrival over the fix, and that time should be reported to ATC. The initial outbound leg is flown for 1 minute at or below 14,000 feet MSL. Subsequently, timing of the outbound leg should be adjusted as necessary to arrive at the proper inbound leg length. Timing of the outbound leg begins over or abeam the fix, whichever occurs later. If the abeam position cannot be determined, start timing when the turn to outbound is completed. The same entry and holding procedures apply to DME holding, except distances in nautical miles are used to establish leg length.
The FAA has three recommended methods for entering a holding pattern, as shown in Figure 7-2. An aircraft approaching from within sector (A) would fly a parallel entry by turning left to parallel the outbound course, making another left turn to remain in protected airspace, and returning to the holding fix. Aircraft approaching from sector (B) would fly a teardrop entry, by flying outbound on a track of 30° or less to the holding course, and then making a right turn to intercept the holding course inbound to the fix. Those approaching from within sector (C) would fly a direct entry by turning right to fly the pattern.

Figure 7-2
If the holding pattern is charted, the controller may omit all holding instructions, except the holding direction and the statement “as published.” Pilots are expected to hold in the pattern depicted even if it means crossing the clearance limit. If the holding pattern to be used is not depicted on charts, ATC will issue general holding instructions. The holding clearance will include the following information: direction of holding from the fix in terms of the eight cardinal compass points; holding fix; radial, course, bearing, airway, or route on which the aircraft is to hold; leg length in miles if DME or RNAV is to be used; direction of turn if left turns are to be made; time to expect further clearance and any pertinent additional delay information.
Example:
(Refer to Figure 87.) At STRUT intersection headed eastbound, ATC instructs you to hold west on the 10 DME fix west of LCH on V306, standard turns. What entry procedure is recommended?
A—Direct.
B—Teardrop.
C—Parallel.
Determine the holding pattern by placing your pencil on the holding fix and dragging it on the holding radial given by ATC, then returning back to the fix. Then draw the pattern from the fix with turns in the direction specified. In this question, ATC has specified standard turns (right turns).
The entry procedure is based on the aircraft’s heading. To determine which entry procedure to use, draw a line at a 70° angle from the holding fix, and cutting the outbound leg at about one-third its length. With the aircraft at STRUT intersection heading eastbound, we are in the largest piece of the pie, so a direct entry would be used. See Figure 7-3.

Figure 7-3
In order to calculate fuel consumption, you must complete the flight log provided with each question. Each question will go through the following steps:
[10-2024]