U.S. Department 

of Transportation 

Federal Aviation 

Administration

Advisory 

Circular

Subject: Change 1 to Simultaneous 

Closely Spaced Parallel Operations 

at Airports Using Precision Runway 

Monitor (PRM) Systems

Date: October 6, 2003 

Initiated by: ATP-100 

AC No: 90-98 

Change: 1 

1. PURPOSE. This change amends Advisory Circular (AC) No: 90-98, Simultaneous 

Closely Spaced Parallel Operations Airports Using Precision Runway Monitor Systems, 

dated February 28, 2003. 

 a. The purpose of this AC is to notify pilots and operators about the establishment 

of specific air traffic procedures to conduct flight operations into airports identified for 

simultaneous closely-spaced parallel approaches using PRM systems. 

 b. The Federal Aviation Administration (FAA) is continuing efforts to expand the 

use of PRM systems at specific airport locations across the country. 

(1) Current PRM operations locations are: 

MSP - Minneapolis-St. Paul International Airport 

PHL - Philadelphia International Airport 

(2) Future PRM operations locations are listed below: 

Note: All airports being considered for PRM operations depending on the results of site 

capability, system efficiency, economic studies, and funding availability. 

STL - Lambert St. Louis International Airport 

SFO - San Francisco International Airport 

ATL - Hartsfield Atlanta International Airport 

JFK - John F. Kennedy International Airport 

CLE - Cleveland Hopkins International Airport 
AC 90-98 10/6/03

The installation of equipment and the implementation of PRM procedures allow 

simultaneous closely-spaced operations to be conducted at airports where parallel 

runways are separated by less than 4,300 feet. 

PRM offers opportunity for increased arrival operations efficiency at airports 

and is important to the economic growth of the National Airspace System (NAS). 

However, to realize the full benefits of using PRM, all pilots flying into airports 

offering PRM services must be able to accept an Instrument Landing System (ILS)-PRM 

or Localizer Directional Aid (LDA)-PRM approach clearance. During the last 5 years 

of PRM operations at MSP, aircraft unable to accept an ILS-PRM clearance have 

caused significant reductions in the number of aircraft arrivals during PRM operations. 

Therefore, the FAA is establishing specific air traffic procedures to offer priority 

services to all aircraft accepting ILS-PRM or LDA-PRM clearances at airports, 

when PRM operations are being conducted. 

2. BACKGROUND. In 1991, the FAA finalized development of criteria for 

implementation of PRM procedures and identified training requirements for air traffic 

controllers and aircrews prior to the start of PRM operations at airports. MSP was the 

first airport to receive approval to conduct closely-spaced parallel approach operations, 

using PRM equipment and specialized procedures. However, for the past several years, 

ILS-PRM approach operations conducted at MSP were impacted by efforts 

to accommodate nonparticipating aircraft requesting services during PRM arrival 

operations. FAA benefits analysis forecast even more adverse operations impact to 

the NAS as PRM systems are expanded, should action not be taken to address 

nonparticipants. 

3. GUIDANCE. To facilitate maximum benefit of PRM systems, the FAA established 

the following guidance for arrival operations into a PRM airport. 

Whereas each pilot in command shall: 

 a. Become familiar with all available information concerning the flight before 

beginning the flight. 

 b. When given, comply with an air traffic control (ATC) clearance or instruction. 

 c. Pilots who are unable to conduct a PRM approach must call the David J. Hurley 

Air Traffic Control System Command Center (ATCSCC) prior to departure to receive 

a precoordinated arrival time. The precoordinated arrival time is good only for the 

day issued. 

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10/6/03 AC 90-98 

When weather conditions and service demands dictate, ATC will conduct PRM operations 

at approved locations to ensure maximum system efficiency and service. Priority handling 

is to be given to all aircraft able to accept clearances to conduct ILS-PRM and LDA-PRM 

approaches. Users can ensure priority service consideration by completing all necessary 

requirements to conduct PRM approaches prior to departure and by accepting a PRM 

approach clearance when offered. When PRM operations are in progress, ATC may, except 

for safety of flight, divert aircraft that have not precoordinated their arrival and are not able 

to participate in PRM operations, to a non-PRM alternate airport. Aircraft that experience 

in-flight equipment or operational problems, and are thereby unexpectedly unable to accept 

a PRM approach clearance, will be afforded appropriate arrival services as operational 

conditions permit. The FAA encourages all operators, when flight planning, to avoid 

designating a PRM airport as an alternate airport unless the operator/pilot has completed all 

requirements for acceptance of a PRM approach clearance. However, the FAA recognizes, 

particularly in the case of international operations, that there are other factors such as 

customs requirements or reciprocal agreements that may limit the availability to certain 

operators of suitable alternate airports. Additionally, the FAA believes that circumstances 

that would result in the need of an international operator to divert to its alternate airport 

would be an extremely rare occurrence, perhaps involving safety of flight issues. 

Accordingly, the FAA would, under those circumstances, provide appropriate arrival 

services as operational conditions permit. 

4. PROCEDURES. ATC will publish the effective hours when PRM operations are 

being conducted. Pilots who are unable to accept a PRM approach clearance must 

contact the ATCSCC directly at 1-800-333-4286 (prior to departure) to obtain 

a precoordinated arrival time. The effective hours for each airport will be published in 

the United States (U.S.) Terminal Procedures publication on the page entitled 

“Attention All Users of ILS Precision Runway Monitor,” or by NOTAM. All users 

intending to arrive at a PRM airport during PRM operations, and not accept an ILS-PRM 

or LDA-PRM approach clearance, must contact the ATCSCC. 

Pilots who arrive at a PRM airport not able to accept a PRM approach clearance, and 

did not contact the ATCSCC prior to departure, should expect an ATC directed divert 

to a non-PRM airport. Pilots who are unable to accept a PRM approach clearance should 

flight plan accordingly for an ATC directed divert to their alternate airport. 

5. USER REQUIREMENTS. To avoid possible divert, undue delay to alternate 

airport, or inadvertent impact on airport operations, pilots must be able to accept 

an ILS-PRM or LDA-PRM approach clearance at airports where PRM operations 

are being conducted. To accept a PRM approach clearance, pilots must review and 

be familiar with the information found in the U.S. Terminal Procedures Publication, 

and be able to comply with published procedures on the page entitled “Attention All 

Users of ILS Precision Runway Monitor,” for the specific PRM airport. For more 

information about user requirements to participate in PRM operations, refer to the 

following: 

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AC 90-98 10/6/03

 a. For general aviation (Code of Federal Regulations [CFR] Part 91) operators, 

the PRM section of the Aeronautical Information Manual, or read the instruction for 

PRM users found at http://www.faa.gov/AVR/AFS/PRMtraining/. 

 b. For commercial operations (CFR Parts 121, 135, and 129), as authorized in the 

company FAA approved operations specifications, see 

http://www.faa.gov/AVR/AFS/PRMtraining/. 

Original signed by Original signed by 

David B. Johnson James J. Ballough 

Director of Air Traffic Director, Flight Standards Service 

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