Time to turn for Procedure Turns

Hello. Yesterday a friend asked me "If you're in a NDB approach, how do you know when to start the procedure turn?"

There's no table for the MAX TIME TO TURN and no DME station. Some VOR/NDB approaches require a procedure turn at 7 or 8 nautical miles from the station, so I've come up with a formula:

If we're flying at 130kts (130 nautical miles per hour) Ground Speed (GS), we divide it by 60. The result would be 2.166666 NM/minute.
If we have to start the procedure turn (PT) at 8NM from the station, we would have to divide it by 2.166666 NM/min. The answer: 3.69 (decimal) or 3:41 minutes (sexagesimal*).

8/(GS/60) and if you want to have an easier formula: (8x60)/GS. Replace the 8 with a 7 if the PT must be made at 7NM.

If the PT must be made at 8NM: 480/GS
If the PT must be made at 7NM: 420/GS

When flying at 100 kts GS and at 7NM a PT must be made, it is: 420/100=4.2 minutes, or 4:12 minutes.

Of course, we could have the different tables in our kneeboard:










If the airport we are arriving at has a DME, then our problems are solved :)

Next post will be a NACO (National Aeronautical Charting Office) chart explanation. Cya.

*Our results are decimal seconds. For a sexagesimal number, we must multiply it by 0.6 (Example: 0.79 minutes. 0.79x0.6=0:47 minutes)

The ILS-DME CATIIIA Approach

Hi. Mexico's only ILS CATIII approach is in Toluca. Other countrys have many more aiports with CATII/III approaches.

Here are the differences of the ILS Categories (ICAO):

a. ILS Category I - An ILS approach procedure which provides for an approach to a decision height not lower than 200 feet (60m) and a visibility not less than 2400 feet (800m) or a runway visual range not less than 1800 feet (550m).

b. ILS Category II (Special authorization required) - An ILS approach procedure which provides for an approach to a decision height lower than 200 feet (60m) but not lower than 100 feet (30m) and a runway visual range not less than 1200 feet (350m).

c. ILS Category III (Special authorization required) -
1. IIIA - An ILS approach procedure which provides for approach with either a decision height lower than 100 feet (30m) or with no decision height and with a runway visual range of not less than 700 feet (200m).

2. IIIB - An ILS approach procedure which provides for approach with either a decision height lower than 50 feet (15m) or with no decision height and with a runway visual range of less than 700 feet (200m) but not less than 150 feet (50m).

3. IIIC - An ILS approach procedure which provides for approach with no decision height and no runway visual range limitations.

Taken from the Jeppesen Airway Manual.

Now here's the Toluca ILS-DME Rwy 15 CATIIIA approach:

So, with the chart in hand, we can see in the header section, appart from the information we already know how to read, we must refer to the minimums section to check the CATIIIA minimums.

In the minimums section we see two parts: CATIIIA ILS and CATII ILS.
· In CATIIIA ILS, the RVR (Runway Visual Range) is presented with readings in hundreds of feet. So in this example, RVR 7 means 700 feet.
· In CATII ILS, the left column lists the lowest available CATII minimum, normally DH 100, visibility RVR 12 (350m). The right column lists the CATII minimum applicable when certain airborne equipment is out of service or when pilot and operator requirements preclude the use of lower minimum. The minimum is normally DH 150, visibility RVR 16 (500m).

With this type of approach, I've finished all approach types there are in Mexico. As I wrote in a previous post, I'll show different charts and approaches.

Bye.

The ILS-DME or LOC Approach

The ILS (Insrument Landing System) approach is the easiest one to make. There are two different ILS approaches: ILS and ILS-DME. So what's the difference? The ILS approach requires a procedure turn to be established on the Localizer (LOC). The ILS-DME approach requires the use of a DME. There are no ILS appraoches in Mexico, only ILS-DME. Example:

The ILS-DME or LOC Rwy 12 is the approach we made to Cancún for our graduation trip. It's special you see :)

Effective Date 16 November 2007. Chart 11-1. ILS Frequency 111.10 Mhz, Identifier: ICUN, Final Approach Course 124º, Glideslope capture at 1300ft (1281' AGL*) 6.0 CUN DME or 4.0 DME ICUN. ILS DA=Descision Altitude is 219' (H=Height is 200') and the airport elevation is 20ft above sea level. Minimum Safe Altitude is 2000ft.
The Missed Approach Procedure is to climb outbound on the 124º radial to 7.0 DME of CUN VOR and then turn right within 10NM to CUN VOR to the minimum holding altitude, which is 2000ft.

There is no ILS-DME1 or 2 for Cancún, because we will be given Radar Vectors to the ILS. Other airports have them, because the procedure starts from an airway, just like the VOR-DME3 of Puerto Vallarta. ATC will clear us for the approach and we will maintain 1300ft and intercept the LOC. At 6.0 DME from the CUN VOR (or 4.0 DME ICUN), we will capture the Glideslope and follow it to our Decision Altitude (or Height). The DA(H) is shown in the minimums section of the chart.

What is DA(H)? It's the altitude (or height) in which you must decide to land or to go around. If we don't have the runway in sight by 219ft, we go around. Checking the minimum section, if we had a C category airplane (A320/B737) we would need at least 1/2 Mile of visibility to land. If the ALS (Approach Lighting System) is out, we would need 3/4 Mile of visibility.

You probably asked yourself why the approach is named ILS-DME or LOC. If the Glideslope is out, we would still have the Localizer. The LOC guides us horizontally to the runway. So, checking in the minimums section, we would have a MDA(H). We would need 3/4 Mile of visibility and if the ALS is out, 1 Mile of visibility.

Look at the table on the profile section. It shows Groundspeeds in knots, the rate of descend with a 3.0º glidepath for the various speeds and the time from the FAF=Final Approach Fix (The small cross at 6.0 DME CUN) to the MAP=Missed Approach Point.
In our A320/737, we would have approximately 140 knots groundspeed. So we would need a rate of descend of 753 feet per minute and the time from the FAF to the MAP would be 1:40 min.

There you go. The next one I will explain is the ILS CATIII approach. Bye

*AGL=Above Ground Level

The NDB Approach

Third post about IFR approaches. This time, the NDB (Non-Directional Beacon) approach. Looks like there's only one NDB approach in Mexico. I will post different approach charts from different countrys later.
The NDB is different from a VOR station.

Ensenada NDB Rwy 11
This NDB approach is more like a VOR approach. You must make a procedure turn in order to land. There's not too much to say. The procedure is very simple: Cross the ENS NDB at 5000ft, descend to 2400ft while flying on the 298º outbound bearing from ENS NDB. Make a left procedure turn and after intercepting the 298º inbound bearing (118º inbound course), descend to the MDA, which is 860ft.
Missed approach procedure is to climb and turn to intercept the 298º bearing outbound to proceed on the approach track to the minimum holding altitude=5000ft.

Note the "CAT A, B & C" on the Header. It means this approach is only for those types of airplane categories. Not 757s or greater. You can see in the minimums section that the category D is not applicable. The night landing is not available, because the runway doesn't have lights.
Check the Circle-To-Land section as well. It is not authorized Northeast of the runway. Reason? Mountains. If you want to circle-to-land on Runway 29, you must do it south-southeast of the runway.

The NDB approach is a very tricky one. It is more difficult than the other types of approaches, because the flight deck instrument only shows the bearing to the station. So if you have a crosswind, it doubles the fun.

Germany has more NDB approaches... I'll post one next time.

The VOR-DME Approach

In this post I'll explain the VOR-DME approach. I haven't wrote the different approaches there are in Mexico:

NDB
VOR
VOR-DME
ILS-DME or LOC
ILS-DME CATII and IIIA

There are many other airport charts, but I'll explain the approach charts first.

The VOR-DME approach has some differences from the VOR approach, but the major difference is that you use the DME (Distance Measuring Equipment). Here's the example:

The VOR-DME Rwy 22 of Puerto Vallarta. As we can see, the difference from a VOR chart is that we fly on a radial and then turn to intercept the inbound course.

Very simple. Crossing the PVR VOR at 5000ft, we fly on the 044 radial 13 DME (13 nautical miles) from the station. After reaching 13 DME, we make a left turn to intercept the 211 inbound course to PVR and descend to 4100ft. When crossing 13 DME on the 211 inbound course, we start our descend to 2600ft. At 8 DME to 1400ft and when reaching 5 DME, we must descend to the MDA. What is our MDA? 720ft.
If we don't have the runway in sight, we execute the missed approach procedure: Climb via the 223 radial to the 7 DME of the PVR VOR, with a teardrop turn to the right within 10NM from the station and level off at the MHA=5000ft.

Now, we have a different type of approach if we are arriving from an airway. The final approach phase is the same (note the (IF) in 15 DME) for all VOR-DME Rwy 22 approaches. This is the VOR-DME 3 Rwy 22:

Why the number 3? Because there are 3 different approach procedures for the VOR-DME Rwy 22 aproach. The difference depends on the airways we are arriving from. Most procedures are made if the airway is near the inbound course of the approach. If we are arriving from an airway from the south or the west, we would use the VOR-DME1 approach. The airways are shown in the chart.

Suppose that we are flying on the V14N/UJ14N airway. We would start our descent so that we cross 50 DME from the PVR VOR at 14000ft. Then we descend to 11000ft at 24 DME and 8000ft to the Initial Approach Fix=IAF, which is 17 DME from the station. We must cross the IAF, unless ATC clears us to fly to the final approach phase.
Now the things become interesting. When reaching the IAF, we must descend to 6000ft and make a 15 DME Arc to intercept the final approach course. Crossing the 052 radial still making the arc, we can descend to 5000ft. When reaching the 039 radial, we descend to 4100ft and intercept the inbound course. The procedure after crossing the 039 radial is the same as the VOR-DME1 procedure.

I personally love this approach. It combines a DME-Arc and a VOR-DME approach. Oh and of course... we land at a famous tropical destination in Mexico ^^.

Next one: NDB approach.

The VOR Approach

Hi there. In this post I'll explain a VOR approach. When flying IFR, you'll have to fly different approaches and departures. The first thing you have to check is the active runway of the airport you're arriving at. In this example I have chosen the VOR Rwy 08 of Mazatlán Airport:

First, you must confirm if it is the correct chart. Sometime pilots take an incorrect chart. It's strange, but it happens. At the top left you can see the ICAO and IATA code of Mazatlán. Below from it, the name of the airport. Then, you must check the Effective Date at the top of the chart: 7 May 2004. It will be effective as long as they don't make a change.

The approach chart is divided in four sections:

Header (Where the airport frequencies, missed approach procedure description, Minimum Safe Altitude and other important data is located).
Plan (A map-like drawing of the approach showing the courses, VORs, terrain and obstructions).
Profile (A vertical-view and preliminary minimum altitudes you'll use as you descend).
Minimums (The Minimum Descent Altitude for the final approach segment and the visibility minimums divided into 4 airplane categories: A is the lightest and D is the heaviest).

The MZT VOR frequency is 114.9 Mhz, Final approach course is 087º (Always magnetic), No FAF meaning No Final Approach Fix, Minimim Descent Altitude is 860 feet (Height 841ft) and the airport elevation is 38ft above sea level.
The circle at the right side of the Header is the Minimum Safe Altitude from the MZT VOR. At those altitudes you won't hit any mountains, towers, cows, etc. There are four different MSAs, because at those cuadrants there are different obstructions at different heights. Between the 180 and the 270 Radial the MSA is 2000ft. There's only water in there, so 2000ft is a safe altitude. Why not 1400ft? because 2000ft is the minimum altitude you must fly above terrain or water or a mountain.

The missed approach procedure (A procedure you have to follow if you don't see the runway at the MAP=Minimum Approach Point or you have to go around for some reason) is to climb outbound on the 102 radial of the MZT VOR, make a right teadrop turn to the VOR within 10NM to the Minimum Holding Altitude (The racetrack-type thing is the holding pattern and shows 4000ft).

On the Plan section of the chart, the approach procedure is drawn with a thick line. The VOR is at the center and the missed approach path is drawn with a dashed line. You can see the obstructions in the area with their heights in feet. The highest obstruction in the area is 2359ft high and it is marked with an arrow.

Now lets shoot the approach: Suppose that we are flying from the Southeast in a slow Cessna 172 doing 80kts groudspeed. You must fly direct to the MZT VOR and then intercept the 267º Radial. You must fly at 4000ft before crossing the VOR. When you crossed the VOR and intercepted the radial, you must descened to 2000ft as in the Profile section is shown and count 6 minutes*. After 6 minutes have passed, you turn left 45º to a heading of 222º and count 1 minute. The minute has passed, so you turn 180º to the right to a heading of 042º.
Then you intercept the 087º course to the VOR and descend to the Minimum Descent Altitude. What is our MDA? Checking the Minimums section, we see that it is an altitude of 860ft. We must maintain 860ft before we have a visual on the runway. The minimum visibility for our type A Category airplane is 1 mile.
If we don't see the runway and cross the MAP=Missed Approach Point (the small M above the VOR in the Profile section), we execute the missed approach procedure to try again.

*Why 6 minutes? There is a table on the Header section: MAX TIME TO TURN is the time you must complete to start the procedure turn. If you have 80 knots ground speed, the maximum time on the 267º course is 6 minutes. With 80kts you cover 8NM in 6 minutes. This is because you must remain inside 10NM from the airport/VOR.

What happens if we arrive from the West? We can't just land straight in. We must cross the IAF=Initial Approach Fix which is the VOR in this approach, so we cross the VOR from the heading we are flying to and after one minute, we fly left or right to the VOR and then make the approach.

What is the CIRCLE-TO-LAND section? When you're on the approach but don't want to land in that runway, because of the winds or the other runway is more comfortable for taxi, you circle to land. If the weather conditions are good, you can do a circling landing. The minimums for this approach on the A category are 860 feet. So when you're maintaining those 860ft, you fly close enough to the other runway so that you keep an eye on it and land. Just like a normal visual pattern. It mixes instrument and visual procedures.

Sounds fun, doesn't it? I've covered most of what the chart shows. The next approach explanations will be shorter, because I won't have to explain the header, minumums, etc.

Stand-by for more :)

More IFR flying... and Star Trek

Hi, I've been very busy (uh lazy too) these days.

I watched the new Star Trek movie. It is AWESOME!!!! The effects, the story, the music! Most of the time I was like WOW! Absolutely brilliant!! It has been long since I saw a good movie. I hope they make more Star Trek movies. I won't make a good review like Aviatrix did, but I wrote my impressions :)

Today I made my last flight on the 172SP I've been flying for the instrument hours. Only 10 flight hours and not 15 as required, because I don't intend to have the instrument rating yet. I learned how to intercept inbound and outbound radials, how to make procedure turns, holding patterns (and the three different entries), DME-Arc and VOR approaches (same as a procedure turn). I don't want to sound too arrogant, but I'm very good at IFR flying :) and most important of all... I really enjoy and like it!
I'll give you different examples of IFR charts in future posts to have something educative.

Oh, I finally have my license!! :D After 3 months waiting I had it on my hand. Yesterday I sent the documents to the FAA in Oklahoma for my license conversion. Lets hope it doesn't take too long... I'm flying to Germany on the 14th July.
It's quite strange to think that my days in Mexico are counted (26 left). I already have a room in Hamburg and now I'm looking forward on planning all the baggage and packing for the flight. My flight route is Guadalajara-Mexico City-London Gatwick-Köln. The first leg with a Mexicana's Airbus A320, the second leg with a MXA's 767-200 and the third and final leg with an Easyjet's Airbus A319.
I'm anxious to be in Germany... I don't know what awaits me, but I like adventures. Everybody is curious to know what happens next, but sometimes curiosity killed the cat (Damn cookie... biggest mistake of my life. Got over it really fast though). You learn from your mistakes and try not to do them again. But everything is part of life :) Everything that can happen to you is part of your life. Good or bad.

I said in my first posts I wouldn't write more about the universe, but here's a wonderful video. Hope you liked it...

Before I publish this post... I lost my Ray Ban sunglasses. Looks like I forgot them in some place while in a hurry to file a flight plan in the airport. I'll just buy new ones.

Good bye. Live long and prosper lol.