Legal Interpretations
Kirkland-AFS-201 2010
Summary
The Question
Must an aircraft dispatcher be able to reach an en route aircraft in less than four minutes to meet the "reliable and rapid communications" requirement of 14 CFR 121.99?
Background
An FAA Flight Standards office (AFS-201) noted that a 1977 FAA "Speed Memo" construed "rapid" in 14 CFR 121.99 as less than four minutes, and sought clarification of the minimum time required for dispatcher communication with an en route aircraft.
The FAA’s Interpretation
Not strictly. After commenters objected to a 2002 proposal to codify the four-minute standard, citing HF radio limitations and satellite equipment costs, the FAA declined to codify it. Because long-range and short-range operations both require reliable and rapid communications under normal operating conditions, the FAA generally considers communications that occur within four to five minutes to meet 14 CFR 121.99.
- Requester
- Kirkland
- Organization
- AFS-201
- Issued
- July 27, 2010
- Subject
- Air Carrier & Commercial Operations
Regulations Cited
Page 1
Federal Aviation
Administration
Memorandum
Date: JUL 2 7 2010
To:
From:
Prepared by: Anne Bechdolt, Acting Manager, Operations Law, AGC-220
Subject: Legal Interpretation of 14 C.F .R. § 121.99
This is in response to your March 23, 2010 request for a legal interpretation of the meaning of "reliable and rapid communications" under 14 C.F.R. § 121.99. You note that a FAA "Speed Memo" dated May 26, 1977, and prepared by Southern Regional Counsel R.R. Hagadone (1977 Speed Memo) stated the FAA continues to construe the tenn "rapid" in § 121 ·.99 as meaning less than four minutes. You seek clarification regarding the minimum time required for an aircraft dispatcher to communicate with an aircraft that is en route and be in compliance with § 121.99.
Section 121.99 states, in pertinent part, that
(a) Each certificate holder conducting domestic or flag operations must show that a tw6-way communication system, or other means of communication approved by the FAA certificate holding district office, is available over the entire route. The communications may be direct links or via an approved communication link that will provide reliable and rapid communications under nonnal operating conditions between each airplane and the appropriate dispatch office, and between each airplane and the appropriate air traffic control unit.
A s stated above, the 1977 Speed Memo construed the tenn «rapid communications" to mean that the calling party must be able to establish communication with the called party in less than four minutes. The FAA sought to codify this meaning into the regulatory text via a 2002 notice of proposed rulemaking_ See 67 Fed. Reg_ 77326, 77334 (Dec. 17. 2002). In response, amajority of commenters objected to the proposed requirement, citing the "diminishing availability of communication service providers who use high frequency (HF) radio communications systems for long-range communications, e.g., oceanic and polar, the limitations of HF voice communications due to propagation characteristics, and the high costs of equipping their aircraft with satellite communication systems which would be one means of meeting these two proposed requirements." 72 Fed. Reg. 31662, 31668 (June 7, 2007).
Page 2
In light of the comments received, the FAA declined to codify a strict less than four-minute rule into the requirements of§ 121.99. The FAA recognizes the concerns regarding current technological limitations associated with long-range operations. However, although long-range and short-range operations take place in different operating environments, each pose safety concerns that nevertheless require reliable and rapid communications under normal operating conditions. Therefore, the FAA generally considers that communications that occur within four to five minutes meet the requirement of"reliable and rapid communications" for normal operating conditions under § 121.99.
Regulations Referenced
Snapshot retrieved August 6, 2026.