PIREP: Racetrack Patterns - Automation NOT included
This month’s PIREP was reported by an operator in South Africa. This was due to a coding issue brought to the attention of Honeywell’s Global Customer Committee where a viable solution was researched to no avail. Unfortunately, ARINC-424 does not provide a means of coding racetrack patterns. Therefore, they will not be in the FMS database and pilots should not expect the FMS to provide guidance to fly the racetrack pattern.
Although not common in the US, racetrack patterns are commonly used in other parts of the world. This PIREP will illustrate the differences between a racetrack pattern and a hold, and how they will look in the FMS.
Holding vs Racetrack Patterns
While holding patterns are very similar to racetrack patterns, they are not entirely the same. A holding pattern is a procedure used predominately in the United States. A racetrack pattern is more commonly used internationally. Both procedures start at a designated facility or fix.
Racetrack Patterns (ICAO Defined)
- Customizable to allow for descent and airspace constraints
- The outbound leg of racetrack procedures can be anywhere from 1 to 3 minutes, specified on the chart in 30 second intervals.
- Maximum airspeeds are aircraft category specific
- Typically have a procedure segment (intermediate or final) imbedded into the inbound leg of the pattern. For these, the start of the procedure segment would be defined as intercepting the inbound course of the racetrack pattern, like a procedure turn in the United States.
- “The length of the outbound track of a racetrack procedure may be limited by specifying a DME distance or radial/bearing from a suitably located facility.” (PANS-OPS Volume II, Part 1, Section 4, Paragraph 3.4.6.)
Holding patterns (FAA Defined)
- Standard pattern is defined
- Leg length (1 or 1 ½ minutes)
- Max airspeed (based on altitude)
- Exceptions to the standard are explicitly charted
- Leg length based on distance
- Non-standard maximum airspeed
- Holding-in-lieu of a procedure turn
The following figure shows how holding and racetrack patterns are depicted on an approach chart and how the Honeywell FMS depicts racetrack patterns as part of flight plans.
Holding Pattern vs. Racetrack Procedure
ARINC-424 does not provide a means of coding racetrack patterns, these procedures are not included in an FMS database, and pilots should expect to manually fly the procedure as depicted on the chart.
As always, if you have questions or comments about this or any other article in the PIREP series, please contact us at FTS@Honeywell.com.
Program Pilot Rob Erlick supports Honeywell NZ FMS 6.1 for Flight Technical Services. He can be reached via email at Robert.Erlick@Honeywell.com.