Upcoming Mono Lake trip
My next upcoming flight is to Lee Vining (O24) near Mono Lake. This will be an overnighter. Fly in Saturday, camp the night, fly out Sunday morning hitting up Lake Tahoe on the return trip. In order to get to Lee Vining I will need to cross my highest terrain yet. I don't have much mountain flying experience but I have read a lot about it and I'm taking extra precautions for this trip.
For route planning, the main things to decide are where to cross the mountains, how to be absolutely sure I'm crossing them in the right place, and what I would do in the event of an in-flight emergency over said mountains.
There are two main choices for mountain crossing locations. Option one is to fly up towards Lake Tahoe where the terrain is significantly lower (7000 feet instead of 10000 feet) and then turn southbound to Lee Vining. This is a more cautious route but it adds about 55 miles to the trip. The other option (the one I have chosen) is to cross at Tioga Pass which is almost directly in line between PAO and O24. Aside from traversing higher terrain, another issue with this route is that I'll be coming over the pass very close to my airport which will still be 5000 below me. It will take some time to bleed off that altitude and get into a position to land.
Not too long ago I read an article (can't remember if it was in AOPA Pilot magazine or on a website somewhere) about a plane crash a couple years ago. The plane was flying from the Oshkosh, WI back to the Bay Area. Somewhere in Utah they were navigating through some high terrain and took a wrong turn. Instead of a mountain pass, they flew into a box canyon. With rising terrain all around and not enough room to make a turn, the plane crashed killing the pilot. With this in mind I want to be extra 100% sure I'm flying where I think I am.
I've spent so much time looking at the chart and at my landmarks, trying to visualize how it will look from the air that it kind of feels like I'm getting ready for my first solo cross country all over again.
VFR sectional chart showing Tioga Pass and Mono Lake area
I will fly outbound from the Manteca VOR on the 068 radial which will put me right over the Hetch Hetchy reservoir. This is a big, long, skinny body of water with a dam on the near end. It's kind of crescent shaped. There are two other reservoirs to the north (left) of my flight path that I'll also be looking out for. Once I hit Hetch Hetchy there will be a river feeding into it from the far end. This river should be in a noticibly pronounced canyon. I'll follow that river/canyon until I get to a paved two lane highway. There will be a bend in the road with a lodge and some buildings nearby. This is highway 120. As long as I keep it in sight and follow it over the pass, I'll be fine. Also the highway will be an option for an emergency landing. Not a super option but better than a granite wall.
So with that out of the way, the other mountain flying issues to consider are wind and density altitude. I plan to be up, over, and back down on the ground by 8:00am which should be before the winds pick up. I've been checking historic wind data for some nearby weather stations and this should give me a good couple of hours before any mountain wave turbulence would kick in.
As for density altitude, the field elevation is 6800 feet and the high temperature calls for 90 degrees F which means a density altitude of about 10000 feet. I plan to depart Sunday morning when it's nice and cool out but even if I had to take off during the heat of the day I'd still manage. Under these conditions the POH gives a takeoff roll of 1410' with 2560' required to clear a 50 foot obstacle. These are both well below the 4000' of available runway. Mono lake itself is 500' below the airport elevation so even in the worst worst case scenario I could point the plane in that direction and circle the lake to pick up altitude.
One other consideration is that I'll be leaving Palo Alto around 6am on Saturday morning. It will almost certainly be overcast and I'll have to depart IFR. The tower will be closed. I will be sure to pick up my clearance via cell phone since Oakland Center and Norcal weren't very helpful to me last time.
The MEA across the Sierras near my intended crossing point is 15100' feet, they really don't want you scraping any mountain tops when you're flying around there IFR! This is a lot higher than a Cessna 172 will go and I don't have supplemental oxygen anyway. Therefore I'll have to cancel IFR somewhere in the central valley and continue at a VFR cruising altitude of 11500 feet. Specific to the Yosemite region is a special law prohibiting flying within 2000 feet of terrain. Since the pass is 9943 feet high, I will have to climb up to at least 12000 as I go through. This is normally a westbound IFR cruising altitude but the nearest IFR traffic will be above me at 15100' or higher so it won't really matter!
I mentioned that on the return flight I will head north to Tahoe instead of flying back direct to Palo Alto. Multiple reasons for this. First, I'd have to climb 6000 feet between taking off and being able to cross over Tioga Pass to the west. Since the airport and the pass are so close this would mean climbing in circles. Lots of circles. If I'm going to burn that fuel to climb I'd rather do it in a straight line and actually go somewhere. Second, there'll be new scenery by taking a different route home. Third, it will give me a lot of options for refueling somewhere (South Lake Tahoe, Carson City, Truckee, etc).
For all the planning I've done for this trip, there's still one thing I don't know about: how to get around on the ground near Mono Lake! I'll report back how that unfolds after the trip.
For route planning, the main things to decide are where to cross the mountains, how to be absolutely sure I'm crossing them in the right place, and what I would do in the event of an in-flight emergency over said mountains.
There are two main choices for mountain crossing locations. Option one is to fly up towards Lake Tahoe where the terrain is significantly lower (7000 feet instead of 10000 feet) and then turn southbound to Lee Vining. This is a more cautious route but it adds about 55 miles to the trip. The other option (the one I have chosen) is to cross at Tioga Pass which is almost directly in line between PAO and O24. Aside from traversing higher terrain, another issue with this route is that I'll be coming over the pass very close to my airport which will still be 5000 below me. It will take some time to bleed off that altitude and get into a position to land.
Not too long ago I read an article (can't remember if it was in AOPA Pilot magazine or on a website somewhere) about a plane crash a couple years ago. The plane was flying from the Oshkosh, WI back to the Bay Area. Somewhere in Utah they were navigating through some high terrain and took a wrong turn. Instead of a mountain pass, they flew into a box canyon. With rising terrain all around and not enough room to make a turn, the plane crashed killing the pilot. With this in mind I want to be extra 100% sure I'm flying where I think I am.
I've spent so much time looking at the chart and at my landmarks, trying to visualize how it will look from the air that it kind of feels like I'm getting ready for my first solo cross country all over again.
VFR sectional chart showing Tioga Pass and Mono Lake area
I will fly outbound from the Manteca VOR on the 068 radial which will put me right over the Hetch Hetchy reservoir. This is a big, long, skinny body of water with a dam on the near end. It's kind of crescent shaped. There are two other reservoirs to the north (left) of my flight path that I'll also be looking out for. Once I hit Hetch Hetchy there will be a river feeding into it from the far end. This river should be in a noticibly pronounced canyon. I'll follow that river/canyon until I get to a paved two lane highway. There will be a bend in the road with a lodge and some buildings nearby. This is highway 120. As long as I keep it in sight and follow it over the pass, I'll be fine. Also the highway will be an option for an emergency landing. Not a super option but better than a granite wall.
So with that out of the way, the other mountain flying issues to consider are wind and density altitude. I plan to be up, over, and back down on the ground by 8:00am which should be before the winds pick up. I've been checking historic wind data for some nearby weather stations and this should give me a good couple of hours before any mountain wave turbulence would kick in.
As for density altitude, the field elevation is 6800 feet and the high temperature calls for 90 degrees F which means a density altitude of about 10000 feet. I plan to depart Sunday morning when it's nice and cool out but even if I had to take off during the heat of the day I'd still manage. Under these conditions the POH gives a takeoff roll of 1410' with 2560' required to clear a 50 foot obstacle. These are both well below the 4000' of available runway. Mono lake itself is 500' below the airport elevation so even in the worst worst case scenario I could point the plane in that direction and circle the lake to pick up altitude.
One other consideration is that I'll be leaving Palo Alto around 6am on Saturday morning. It will almost certainly be overcast and I'll have to depart IFR. The tower will be closed. I will be sure to pick up my clearance via cell phone since Oakland Center and Norcal weren't very helpful to me last time.
The MEA across the Sierras near my intended crossing point is 15100' feet, they really don't want you scraping any mountain tops when you're flying around there IFR! This is a lot higher than a Cessna 172 will go and I don't have supplemental oxygen anyway. Therefore I'll have to cancel IFR somewhere in the central valley and continue at a VFR cruising altitude of 11500 feet. Specific to the Yosemite region is a special law prohibiting flying within 2000 feet of terrain. Since the pass is 9943 feet high, I will have to climb up to at least 12000 as I go through. This is normally a westbound IFR cruising altitude but the nearest IFR traffic will be above me at 15100' or higher so it won't really matter!
I mentioned that on the return flight I will head north to Tahoe instead of flying back direct to Palo Alto. Multiple reasons for this. First, I'd have to climb 6000 feet between taking off and being able to cross over Tioga Pass to the west. Since the airport and the pass are so close this would mean climbing in circles. Lots of circles. If I'm going to burn that fuel to climb I'd rather do it in a straight line and actually go somewhere. Second, there'll be new scenery by taking a different route home. Third, it will give me a lot of options for refueling somewhere (South Lake Tahoe, Carson City, Truckee, etc).
For all the planning I've done for this trip, there's still one thing I don't know about: how to get around on the ground near Mono Lake! I'll report back how that unfolds after the trip.