ACS Task IR.V.B — Departure, En Route, and Arrival Operations

What is ACS Task IR.V.B?

ACS Task IR.V.B — Departure, En Route, and Arrival Operations — sits within Area of Operation V (Navigation Systems) of the Instrument Rating Airman Certification Standards (FAA-S-ACS-8C) . It evaluates your ability to read, brief, and execute published departure and arrival procedures, manage enroute altitudes, and interpret complex clearances such as "climb via SID" and "descend via STAR."

This task is closely related to IR.V.A (Intercepting and Tracking Navigational Systems), which covers the lateral navigation skills you apply when executing the procedures here. Where IR.V.A tests whether you can track a course, IR.V.B tests whether you understand the full procedural framework — what altitude to be at, what speed restriction applies, and what authorization is required to deviate from any of it.

What is the difference between an ODP and a SID?

An ODP (Obstacle Departure Procedure) provides obstacle clearance and is always available to the pilot — no explicit ATC authorization is required. A SID requires an explicit assignment in your IFR clearance before you may fly it.

AIM 5-2-9 defines the ODP as a procedure designed solely to provide obstacle clearance after departure. ODPs appear in the front section of the Terminal Procedures Publication (TPP) for the relevant airport. When no SID is assigned, pilots are expected to fly the published ODP if one exists — silence from ATC does not mean obstacle clearance is guaranteed by ATC radar coverage.

Per AIM 5-2-7, a SID comes in two forms. A pilot-NAV SID has a charted lateral path that you navigate independently, following depicted fixes, courses, and DME distances. A vector SID relies on ATC radar vectors to establish you on the route — you fly assigned headings until ATC directs you to resume own navigation.

What does "climb via SID" mean — and what does it require?

"Climb via SID" is a defined ATC clearance shorthand described in AIM 5-2-8 . When ATC issues "Cleared [departure], climb via SID," you are required to:

1. 1
   Fly the published lateral path of the SID exactly as charted, including all fixes, courses, and DME-based waypoints.
2. 2
   Cross every fix at its published altitude restriction. "At or above" restrictions are minimums; "at or below" are maximums; "at" means exactly at that altitude. Do not level off between fixes unless a restriction requires it.
3. 3
   Comply with all published speed restrictions. Speed limits on the SID (e.g., "250 KIAS maximum below 10,000 feet MSL") are mandatory — they are not advisories.
4. 4
   Climb to the top altitude. The top altitude on a climb-via clearance is your cleared altitude for the SID. Do not climb above it without further ATC authorization, even if a fix restriction is lower than the top altitude.

The critical distinction: if ATC omits "via SID" and issues only "Climb and maintain [altitude]," you are cleared to the assigned altitude and are not required to comply with intermediate SID altitude restrictions — though you must still fly the lateral path if the SID was assigned.

What are MEA, MOCA, and MCA — and how do they differ?

These three minimum altitudes govern en route IFR flight. The underlying regulatory requirement is 14 CFR 91.177 , which requires you to fly at or above the applicable minimum altitude at all times — 1,000 feet above the highest obstacle within 4 nautical miles of the course in non-mountainous areas, and 2,000 feet in designated mountainous areas.

Per AIM 5-3-3, the MOCA guarantees the same obstacle clearance as the MEA throughout the segment, but navigation signal (VOR) is only guaranteed within 22 nautical miles of the defining VOR. If you are between two VORs and each is more than 22 nm away, the MOCA does not guarantee usable signal reception. Flying the MEA always guarantees both obstacle clearance and nav signal for the full segment.

An MCA is published when the MEA on the next segment is higher than the MEA on the current segment and a specific fix must be crossed at or above a minimum altitude to ensure obstacle clearance during the subsequent climb. MCAs appear on en route charts as a flag symbol with the altitude and applicable direction.

What does "descend via STAR" require?

"Descend via" is a clearance shorthand defined in AIM 5-4-1 . It is the arrival analog of "climb via SID." When ATC issues "Descend via the [STAR name] arrival," you must:

• Fly the published lateral path of the STAR, including all transitions and routing.
• Cross altitude-restricted fixes at their charted altitudes. Published altitudes on a STAR serve as both minimums (bottom altitudes) and maximums (top altitudes). A fix charted "at or above 8,000" is a minimum; "at or below 10,000" is a maximum; "at 9,000" means exactly 9,000.
• Comply with all published speed restrictions on the STAR (e.g., "250 KIAS or less when below 10,000 feet MSL" from 14 CFR 91.117).
• Descend from the top altitude of the STAR clearance without leveling off unless a fix restriction requires it. You manage the descent profile — ATC is not issuing step-down altitudes.

If ATC issues "Descend via the STAR except maintain [altitude]," the assigned altitude overrides the STAR top altitude. You still comply with all intermediate fix restrictions below that altitude, but you do not descend below the assigned altitude until further clearance.

What does the DPE look for under IR.V.B?

The DPE evaluates chart-reading skill, clearance interpretation, and altitude discipline throughout the flight. On the oral portion, expect scenario-based questions that require you to decode a specific SID or STAR procedure from a chart — not just recite definitions.

During the flight portion, the DPE watches whether you actually comply with SID/STAR altitude and speed restrictions as you fly them, and whether you cross mandatory fix altitudes within ACS tolerances (+100/-0 feet for altitude at mandatory-altitude fixes).

What are common errors on IR.V.B?

• Leveling off at an intermediate SID altitude when "climb via" was issued. This violates the clearance — you must continue to climb through each restriction to the top altitude.
• Confusing MEA and MOCA. Candidates often state that both guarantee nav signal. Only the MEA guarantees signal for the full segment; the MOCA only guarantees it within 22 nm of the VOR.
• Flying below the ODP after departure because ATC did not assign a SID. Absent a SID, the ODP is the pilot's responsibility — not ATC's.
• Missing speed restrictions on SIDs/STARs. Charted speed restrictions are mandatory when "climb via" or "descend via" applies. Treating them as advisories is a clearance violation.
• Ignoring the MCA flag at a fix and descending or crossing below the required altitude before beginning the climb to the next segment's MEA.
• Misreading top vs. bottom altitude restrictions on STARs. Candidates sometimes cross a "at or above" fix too high because they treated it as a maximum rather than a minimum.

Frequently Asked Questions

Q: What is the difference between an ODP and a SID?

An ODP (Obstacle Departure Procedure) provides obstacle clearance and is always available to the pilot without ATC authorization. A SID is an ATC procedure that requires explicit assignment in your clearance. When a SID is not assigned, pilots should use the ODP for terrain/obstacle avoidance during departure.

Q: What does "climb via SID" mean in your clearance?

Per AIM 5-2-8, "climb via" is a shorthand clearance requiring you to comply with the SID lateral path, all published altitude restrictions, and all published speed restrictions. You may not level off at an intermediate altitude — you must cross each fix at its charted restriction unless ATC explicitly amends it.

Q: What is the difference between MEA and MOCA?

Both protect you from terrain and obstacles, but the MEA also guarantees navigation signal reception (VOR within 22 nm). The MOCA provides the same terrain/obstacle clearance as the MEA but only guarantees VOR signal reception within 22 nm of the VOR. Flying the MOCA beyond 22 nm of a VOR may leave you without usable nav signal.

Q: What does "descend via STAR" mean?

Per AIM 5-4-1, "descend via" requires you to comply with the STAR lateral path, all published altitude restrictions ("top altitudes" as maximums and "bottom altitudes" as minimums at each fix), and all published speed restrictions throughout the procedure.

Q: Can you descend below the MEA on your own initiative?

No. Under 14 CFR 91.177, you must maintain the MEA (or other applicable minimum altitude) unless ATC issues a lower clearance or you are established on an approach procedure. The MEA exists to protect you from obstacles and ensure nav signal integrity — neither guarantee applies below it.

Q: What is a Minimum Crossing Altitude (MCA)?

An MCA is the lowest altitude at which you may cross a specific fix when proceeding in a specific direction. MCAs appear when the MEA on the next segment is higher than the MEA on the current segment and a crossing altitude is needed to ensure obstacle clearance during the climb.

Q: Are you required to fly a SID if one exists at your departure airport?

No — a SID must be explicitly assigned in your clearance. However, unless a "No SIDs" note appears in your remarks, ATC will often assign one at busy airports. If no SID is assigned, you are expected to use the published ODP for obstacle clearance.

Q: What is the difference between a pilot-NAV SID and a vector SID?

A pilot-NAV SID has a charted lateral path you navigate independently. A vector SID requires radar vectors from ATC; the chart shows the general flow but ATC directs your turns. On a vector SID, you fly assigned headings until ATC clears you to resume navigation on the route.

Sources

• FAA Instrument Rating ACS (FAA-S-ACS-8C)
• AIM Chapter 5-2-7 — Departure Procedures (SIDs)
• AIM Chapter 5-2-8 — Climb Via Clearances
• AIM Chapter 5-2-9 — Obstacle Departure Procedures (ODPs)
• AIM Chapter 5-3-3 — En Route Navigation (MEA, MOCA, MCA)
• AIM Chapter 5-4-1 — Standard Terminal Arrivals (STARs) and Descend Via
• 14 CFR 91.177 — Minimum Altitudes for IFR Operations
• FAA Instrument Procedures Handbook (FAA-H-8083-16B), Chapters 2–3
• FAA Instrument Flying Handbook (FAA-H-8083-15B)

This article was researched from FAA primary sources (ACS, FAR/AIM, Advisory Circulars, Instrument Procedures Handbook) and citing current 14 CFR Part 91 — drafted by MockDPE. Last updated: May 2026. If you spot an inaccuracy, email corrections@mockdpe.org.