Military Training Routes

[FlyingOnFumes]

While reviewing various charts, I started to wonder:

How are IRs defined? (i.e. What defines one?)

I understand how VRs can be arbitrary since they are VFR (and can be flown by visual checkpoints/landmarks) and...

I understand how victor airways and jet routes are defined.... between VORs and/or VORTACs along certain reciprocal radials or cross radials for a bend intersection... but mostly navaid to navaid.

but looking at the various charts, seems like most IRs are arbitrary in where they begin, end, without regards to any TACAN or VORTAC etc... radials to follow.

I've only seen a handful of IRs in the IFR charts i'm looking at that seem to be offset from a navaid radial at a certain DME distance ("RNAV" style), but most (on cursory look) seem to be not based on any navaid. Are they just using lat/long coordinates to define them? How are they flown in real life? Back in the day before GPS, did it require some sort of INS to follow the route if they were not following a navaid radial.

 

[JD81]

VR/IR's use lat longs and sometimes navaid radial/dme's, you would want to reference an AP/1B pub if you have access to one, lists every MTR in the country.

 

[ea6bflyr]

Visual and Instrument Routes are defined in the AP-1B and they have corridors and altitudes associated with each. Each route has an owner and the routes serve several purposes. Visual Routes can only be flown in VMC whereas Instrument Routes can be flown in IMC and VMC. Visual Routes are generally used to practice VISUAL NAVIGATION using Dead Reckoning (DR) navigation (Heading/Distance/Rate/Time).

The training commands use the VR's to help students practice Terrain Clearance Tasking while accomplishing Mission Tasking. One of the hardest things to master is timing.

The IRs are used for various purposes as well. We can fly an IR as a VR. Advanced NFO training uses the IRs for Radar Navigation (still uses basic DR).

Most of the routes are arbitrary and use terrain to define the route. They are not based on NAVAID location, but the points along the route can be defined off of local NAVAIDs.

-ea6bflyr

 

[Brett327]

VR/IR's use lat longs and sometimes navaid radial/dme's, you would want to reference an AP/1B pub if you have access to one, lists every MTR in the country.

IR and VR are the same in many respects. I have never seen an IR or VR point defined by anything other than a TACAN cut. There are IRs that start or remain at a relatively high altitude, but the ones we fly in the Pac NW are all essentially low level routes that are flown under an IFR clearance, meaning that you tell the controller your expected entry and exit times, and you stay in radio contact with ATC the whole time.

Brett

 

[FlyingOnFumes]

The training commands use the VR's to help students practice Terrain Clearance Tasking while accomplishing Mission Tasking. One of the hardest things to master is timing.

The IRs are used for various purposes as well. We can fly an IR as a VR. Advanced NFO training uses the IRs for Radar Navigation (still uses basic DR).

Most of the routes are arbitrary and use terrain to define the route. They are not based on NAVAID location, but the points along the route can be defined off of local NAVAIDs.

If following an IR with RADAR, do you mean Synthetic Aperture ground mapping radar and/or terrain following radar?

If going point to point (vice following a radial), would that require some sort of advanced navigation capability such as inertial or other nav computer that can create a course line for you to follow under IFR in IMC?

 

[mmx1]

If going point to point (vice following a radial), would that require some sort of advanced navigation capability such as inertial or other nav computer that can create a course line for you to follow under IFR in IMC?

SWAG from the other side of the house, but I believe that "advanced navigational capability" is a NFO.

Or on our side, a pencil.

 

[ea6bflyr]

If following an IR with RADAR, do you mean Synthetic Aperture ground mapping radar and/or terrain following radar?

We use an air-to-ground radar to map the terrain, specifically the APG-66NT which is a modified version of the F-16 radar. See AVATAR to the left for an example of the radar display we use.

If going point to point (vice following a radial), would that require some sort of advanced navigation capability such as inertial or other nav computer that can create a course line for you to follow under IFR in IMC?

Most of the time, you are too low or too far to receive the NAVAID signal. Low Level navigation is based on DR. BTW, DR is the basis for how INS works. You fly a defined Heading at a specific groundspeed for a certain time to cover a specified distance.

Point-to-Points are a bit more difficult to explain over the internet. Anyone want to give that one a shot?

-ea6bflyr

 

[Brett327]

We use an air-to-ground radar to map the terrain, specifically the APG-66NT which is a modified version of the F-16 radar. See AVATAR to the left for an example of the radar display we use.



Most of the time, you are too low or too far to receive the NAVAID signal. Low Level navigation is based on DR. BTW, DR is the basis for how INS works. You fly a defined Heading at a specific groundspeed for a certain time to cover a specified distance.

Point-to-Points are a bit more difficult to explain over the internet. Anyone want to give that one a shot?

-ea6bflyr

Fixed that for you. Anyhow, point-to point is easy - just hit the direct button on your FMS thingie.

Brett

 

[magnetfreezer]

Point-to-Points are a bit more difficult to explain over the internet. Anyone want to give that one a shot?

Most military aircraft with VOR/TACAN capability have HSI-format displays (i.e round compass card with pointer that displays what radial you are on) instead of CDI-only from GA avionics (someone feel free to correct me on this, GA experience limited to IFS '172s).

We can fly point-to-point by tuning the navaid and then using the HSI to visualize our location in relation to the navaid - i e on the 090 radial at 20 miles. You can then visualize the desired fix - 360 at 50 - and estimate a good initial heading based on that. As you proceed toward the point, continue to iteratively correct your solution.

Many HSIs often have a CDI needle as well; this leads to the "pencil method" of using the dial as a virtual chart. The center is the navaid; the outside then becomes the greater DME (in this case 50). Since the VOR/TACAN needle always points toward the station, the aircraft will be on the "tail half" of the needle at the appropriate DME (in this case, 20DME/50DME=2/5 of the way up the needle).

The desired fix is then located with the CDI needle (in this case, turn to 090 and the fix is on the outside of the dial). A pencil/other straightedge can then be put between those 2 points and then slid to the center to read off the heading on the dial.

This is generally the initial way point-to-points are taught; later the use of pencils/objects in the cockpit is discouraged for FOD concerns and we visually estimate connecting the 2 points; finally, the CDI needle is not needed at all since after some practice you can estimate the heading using only the dial and VOR/TACAN needle.

 

[C420sailor]

...words on VOR/TACAN pt to pt...

Are you trying to tell me that we're not supposed to break out the whiz wheel for this...?

 

[scoolbubba]

I haven't used a whiz wheel since IFS. It's easier just to stick your pencil or a finger up against the RMI/HSI and figger it out.

 

[vick]

Pt to pt - why in allah's name would anyone do that to themselves? And what is this DR you keep talking about in reference to MTRs?

These days most any tactical jet on a low-level ingress/MTR is going to be using an INS with embedded GPS and aided by a moving map and a HUD. The timing is a no-brainer which frees up mental RAM for things like keeping track of your wingman and executing your actions at the IP.

 

[nittany03]

Pt to pt - why in allah's name would anyone do that to themselves? And what is this DR you keep talking about in reference to MTRs?

These days most any tactical jet on a low-level ingress/MTR is going to be using an INS with embedded GPS and aided by a moving map and a HUD. The timing is a no-brainer which frees up mental RAM for things like keeping track of your wingman and executing your actions at the IP.

As a pilot-to-NFO retread GPS/INS/HUD cripple who just finished VT-86's A/G syllabus . . .

BURN. :icon_tong

 

[scoolbubba]

Pt to Pt =Trazing. I love how on any flight where ATC clears me "direct BOGER maintain 3000 cleared tacan 31 into yadda yadda," while I'm executing my point to point, the IP is furiously typing BOGER into our GPS and making sure I'm not dicking it up.

 

[CommodoreMid]

I think my favorite was on an INAV ride ATC asked me if I wanted direct CEW or PENSI. Definitely jumped on the CEW option before the IP could key the mike It's not cheating, it's taking the easy way out.