Navigational
equipment required:By Andrew Herd
Navigational
equipment required:Standard basic avionics fit plus ACS-GPS
The Kodiak scenery by Dennis Waggoner for FS2000 will add to the experience.
Kodiakgps.zip - extract all these files into your \FS2000\pilots folder
Kodiak.prg - ACS-GPS file to load into \FS2000\ACS-GPS\programs (or whatever folder your ACS-GPS setup keeps its program files in)
This is a non-precision GPS approach and the tutorial assumes that you understand the basics of GPS navigation and can operate ACS-GPS.
Please make sure you have Indicated Airspeed (IAS) set. If you have True Airspeed set, the instructions which follow will make no sense at all. Also, ensure that you do not have gyro drift checked under the realism settings, unless you are proficient at making corrections for this. Do not use the Microsoft GPS window on pain of death. If you do not have appropriate approach plates, click on the image at the top of this page to view a Final Approach plate courtesy of Georges Lorsche.
Situation 1: Non-precision approach GPS Rwy 25 - select flight kodiakgpsporter
The
flight starts with the aircraft approaching ODK at 2600 feet on a heading of
091. Make sure that ACS-GPS is switched on in passive mode and that ODK is the
active waypoint. Trim the aircraft, and maintain heading and altitude. When
the distance to ODK zeros, alter your heading to 115 and maintain altitude.
Switch to the next waypoint (KIHYO) and prepare to cross it in 2.2 nm.
After crossing KIHYO, the profile shows that we have to execute a course reversal - but how? The answer is to use the holding pattern shown in the plan view. After crossing KIHYO, set your heading bug to 069, and twist the course on the HSI to 249 - this is just as a reminder of the inbound course, because this isn't a precision approach and we will will not be tuning the ILS. Time one minute outbound on a heading of 069, maintaining altitude, then turn to port, swinging round to 249. This course reversal will leave KIHYO, which is the FAF, somewhere to our left, because of the distance we have covered in the turn. How do we find where it is? Easy, look at the GPS. If KIHYO is still tuned, the instrument will tell us exactly what heading it is on.
At
this point, you may be asking why we executed the manouever we just did, but
you can congratulate yourself on having performed a parallel entry into a holding
pattern. If we needed to lose a lot of altitude, we would make a turn to starboard
on crossing KIHYO again, fly outbound on 069 for one minute, turn again and
then fly back in to KIHYO on 249, but we can easily lose 300 feet without doing
that, despite the turbulence.
When I tested this and completed the course reversal, the bearing to KIHYO was 209, so all I had to do was make an alteration of around 30 degrees of course to head straight for it. Your bearing may be different by a few degrees. If you find you need a 90 degree turn to make it, you need to go pump some iron to help get that bird around faster.
Once the aircraft is stable inbound to KIHYO, reduce power some and descend to 2300. When the distance to KIHYO zeroes, you are at the FAF, and you can begin a descent again to the MDA on a course of 249. The MDA is 500 feet for the Porter and the MAP is located at the ELEVE intersection, which is the third waypoint in the GPS, so switch to it now.
The
final segment is long enough for the wind to give you a problem and it is here
that one of the strengths of ACS-GPS becomes apparent. If you keep comparing
the aircraft's heading to the GPS bearing to ELEVE, it will instantly become
apparent if you are drifting off track to any significant extent. If this happens,
just double the difference between the aircraft's heading and the GPS indicated
heading and alter your course by that amount until the GPS reads 249 again.
After you have done this once or twice, you will have a good idea how much permanent
wind correction you need to stay on track.
The Porter's low stalling speed and generally good low speed handling means that you have nearly forever to make the descent, if you are prepared to go slow enough. The one problem is whether you will be visual at the MAP. Despite the weather, I reckon you will probably get in.
"Do
you remember them telling us anything about one of those on the clearance, Al?
Reckon we ought to mention it to someone, or should we just dodge around it?"
"Well ah dunno, Andy, I guess this is Alaska. But if he heads off that way he is gonna hit that mountain for sure. Maybe it would be polite to ask if he's lost, or something?"
"Er...Kodiak tower, Porter 673MR on short finals runway 25. There's some guy parked in a 737 on the threshold changing a tire - if we drop some flap there may be time for you to ask him to move over."
"Porter 673MR, Kodiak tower, that's just an FSTraffic plane, you are cleared to land."
Situation 2: Non-precision approach GPS Rwy 25 - select flight kodiakgpsporter88
This
is not a good situation. You have had a bad trip and you are approaching ODK
on 091 again, but at an altitude of more than 7000 feet. You have a couple of
paying passengers in back, so resist the urge to stand the Porter on its nose
and coast down in the beta range while you hang in the straps. No way can you
afford to descend more than a thousand feet per minute. It is windy, there is
8/8 cloud and it is raining from time to time as well. You also need a pee (you
can simulate this by drinking four cups of coffee and then loading this flight).
Sticking to these rules, I managed to descend to just over 4000 by the time I had completed the course reversal and returned to KYHO, which would have meant losing another 3500 feet before the MAP at Eleve - not a good idea in these conditions, even if I hadn't anyone in back. ATIS was telling of marginal visibility, but if there ever was a plane that lets you fly safely to the limits, the Porter is it, so after checking the missed approach procedure a second time, I decided we would go down and take a look. We were just going to have to do a circuit of the holding pattern to lose that altitude.
When you reach KIHYO, turn right onto a course of of 069 again - you should already have the heading bug set up. Start the timer and fly outbound for one minute. When the minute is up, turn right again, watching the GPS, and when the bearing is nearly at 249, turn onto the inbound course. If you lose altitude on both legs, you should be down to 2300 by the time you cross KIHYO inbound again, but you will find that the wind has pushed you well off track, and you will need to make a fairly substantial correction to maintain the track to the MAP. As you cross the FAF, tune ELEVE and configure for landing. Will you meet the minimums at the MAP? Well, you are gonna have to fly there and find out (-:
Andrew Herd
