TERPS

Terminal Instrument Procedures

TERPS
THE TERPS
8260.3B 436 pages of TERPS goodness
Provides the criteria used to formulate, review, approve, and publish instrument flight procedures for operations to and form civil and military airports
8260.19E 469 pages
Provides guidance to all FAA personnel for the administration and accomplishment of the FAA flight procedures and Airspace Program

CFIT
So how do you know when you start your takeoff roll, you’re not going to hit anything?

The OCS and ROC
Obstacle Clearance Surfaces
These are used to determine the minimum climb gradient over obstacles
Required Obstacle Clearance
The normal minimum climb gradient that provides required obstacle clearance is 200fpnm(300fpm@90kts)

The 24% Rule
The difference between the OCS and the ROC turns out is 48fpnm
The OCS gains altitude at the rate of 152 fpnm
The ROC gains altitude at the rate of 200fpnm
That leaves a difference of 48fpnm
Take .24×200=48
This means for every 1NM you gain 48 feet above the OCS

Departure to Enroute
The OCS is applied during the climb all the way up to the enroute ROC
The OCS starts at the departure end elevation and goes up from there
It is assumed the aircraft will cross the departure end of the runway at least 35 feet
It is also assumed the aircraft will climb to 400 feet AGL before turning

Diverse Departure Assessment
Ensures an expanding amount of ROC is achieved during the climb out until the aircraft can obtain the 1000 in non-mountainous and 2000 in mountainous
Typically this is achieved at 25NM for 1000 feet of ROC
46NM for 2000 feet of ROC
Why?
The 200fpnm provides a 48fpnm clearance above the OCS
25X48=1200 feet
46-25=21 21×48=1008
Acquisition of positive course guidance is designed in so that it occurs within 5-10NM from the DER
Remember, you are responsible for obstacle clearance if not operating on a published airway (MEA)

Procedure Construction
There are 4 segments:
Initial
Intermediate
Final
Missed approach
Usually these segments begin and end at fixes, however if no fix exists, then at a specified point
When designing the approach they start with the final approach course because it is the least flexible in its placement

The 4 Segments
Feeder Routes
In a non radar environment they will put more feeder routes on the chart
In radar environments they will put at least 1 in case radar goes down
The standard 1000 non-mountainous and 2000 mountainous applies
Descent gradients on feeders
250fpnm optimum
500fpnm max
High attitude optimum is 800fpnm
High altitude max is 1000fpnm

Minimum Safe Altitudes
Denoted as a circle on the planview
Specified distance usually 25NM
Centered on the primary navaid
Altitudes give 1000 feet obstacle clearance or more
Values are rounded up to the next higher 100 foot value
Sectors must be no less than 90 degrees apart

Lead Radials
The intermediate and the initial approach course must be aligned within 120 degrees max
If greater than 90, a lead radial must be published to give at least 2NM of lead
You see these on approaches with arcs, identified as LR
The smallest arc you’ll ever see is 7NM
Initial Approach Segment
Required obstacle clearance (ROC) for the initial segment is 1000 feet for the primary, 500 tapering to 0 for the secondary

Procedure Turns
Have to stay within 10NM
Primary area gives 1000 clearance
Secondary area 2NM 500 feet tapering to 0
Teardrop procedure turns are to allow aircraft to loose a lot of altitude in a limited space
If a procedural track is published you have to fly it

ARCs
The ROC along the arc depends on the approach segment
For the initial approach segment
ROC of 1000 feet
For the intermediate approach segment
ROC of 500 feet
The primary area is 8NM wide

ARCs
Calculating The Final Approach Segment

Circling Approach
Gives 300 feet over the highest obstacle in the circling area

Missed Approach
The OCS starts at the Missed Approach Point MAP
The ROC increases as the missed approach route progresses
The OCS is applied until reaching the minimum initial or enroute value of the ROC

Missed Approach
In the primary area a 40:1 slope (152fpnm)
In the secondary area a 12:1 slope