Overview: up close and personal with a DC-7 tanker

Over the course of the last several months, I have run into various references about the Douglas DC-7 air tankers on the web and in books and magazines. Over the summer I saw an article, probably from an Oregon newspaper with a photo of a DC-7 tanker then under contract to Oregon. Recently, I again saw references to DC-7 tankers being under contract to California, this time through an electronic bibliographic database that I accessed through my local public library. Now, I have always had a fondness for the various aircraft in the Douglas DC series, so I asked one of my airtanker pilot friends about these DC-7 tankers. I was lead to Butler Aircraft and then to Larry Kraus, a veteran tanker pilot who has been captain of one of Butler's three DC-7 airtankers.

I have been corresponding with Larry Kraus for the last several days. Thank-you Larry!! This correspondence plus this thread on Butler's tankers, started by Larry on the Warbird Information Exchange forums, form the basis for a series of articles on the DC-7 tanker. Please sit down and join me as we get up close and personal with these beautiful and historic tankers.

Upcoming topics include:

Dec. 7: introduction to Butler's DC-7 tankers and a little history
Dec. 8: specifications - pt. 1
Dec. 9: specifications - pt 2:
Dec. 10: engine maintenance pt 1 and pt 2
Dec. 11: shots of the former passenger cabin of T-62, ballast
Dec. 12: former passenger cabin continued, floating beam
Dec.14: the cockpit
Dec. 16: retardant drop cockpit controls and the drop sequence
Dec. 18: more on the drop sequence
Dec. 21: action shots pt 1
Dec. 23: action shots pt 2
Dec. 30: my reflections

Edited to add a revision I made at Larry's request on March 1, 2010: revisiting ballast, weight and balance, and fuselage stations

K-MAX around the world

Kaman K-MAX

When I was coming up with the list of type 1 helicopters that I just finished writing about, I came upon the Kaman K-MAX. If you have watched the video that I have embedded from the July 2009 airshow in Binghamton NY, then you have seen that the K-MAX has no tail rotor. The K-MAX is a different kind of helicopter using something that is known as synchropter technology where there are contra-rotating, inter-meshing rotor blades. In this design, a tail rotor is not necessary.

The K-MAX is designed for heavy lifting, where it is rated to lift 6,000 pounds with its cargo hook. For specifications, go here. A couple of videos, including a ten minute video introducing the K-MAX, "K-MAX around the world" may be found on this Kaman K-MAX web page. This same video may be found on you tube, I'll make a post embedding that video a little later.

The fire fighting version of the K-MAX is known as the FIREMAX. The FIREMAX has a 700 gallon fixed tank, and I believe that it also has the capacity for bucket operations although I'm not sure how large the bucket is.

Aviastar has a page with information about the K-MAX at this location.

Sikorsky S-64/CH54

Direct link to video


Direct link to video


Direct link to video

I have written extensively about the Erickson Air Crane, so you may recall that Erickson purchased the manufacturing rights and type certificate for the Sikorsky S-64E and S-64F from Sikorsky in 1992. You may also recall that the S-64 is the civilian version of the military CH-54. In addition to manufacturing "new" Aircranes, Erickson refurbishes military CH-54 for civilian use.

Some photos and specifications of the CH-54 may be found here. Wikipedia's entry on the CH-54 may be found here.

As I end this series on type 1 helicopters, I wanted to mention that there are some S-64 "Skycranes" that are flying that are not Erickson Aircranes. Most of these are refurbished military CH-54's. One of these Skycranes is shown in the video.

Edited and updated on November 20, 2017: the video that I originally embedded here is no longer available, so I have embedded three short videos of the CH-54, two are stock footage from Vietnam and the last is from a 1991 airshow. In addition, I have removed two dead links and replaced the links with what I hope is similar information.

Helicopters: S-58

One of the most successful helicopters ever built is the Sikorsky S-58/H-34. The military version is the H-34 Choctaw, serving in the armed forces of over 25 countries. This piston-powered helicopter was first flown on March 8, 1954. Sikorsky developed a turbine conversion kit for the S-58, the S-58T, which first flew on August 19, 1970. There are very few of these models still flying today, and as I understand it, most are used in firefighting and construction operations. I think, but am not quite certain, that the S-58 qualifies as a type 1 helicopter for firefighting, so I am writing about it now.

California Helicopters specializes in refurbishing S-58 and S-58T helicopters. They have a webpage with photos and specifications and another page with weights, performance and design specs.

Desiree Horton, a helicopter pilot who writes The Adventures of a Chopper Chick! weblog has (or still does?) fly the S-58. She summarizes the history of the S-58 here..

Wikipedia has a page on the H-34/S-58 that includes some photos and information on the different variants.

Type 1 helicopters: S-70

The military counterpart of the civilian Sikorsky S-70 helicopter is known as the UH-60 "Black Hawk". The first prototype of the UH-60, a design replacement for the Bell UH-1 or Huey series of helicopters, entered service in October 1974. It entered service in the U.S. Army in 1979.

In addition, there is a nice write-up (with some pictures) of the many variants of the UH-60 and the S-70 here, note that this is a MS Word document. The many variants make direct comparisons difficult.

The firefighting version of the S-70 is known as the Firehawk. The Firehawk can be fitted with a removable 1,000 gallon fixed tank. Existing Black Hawk's can be converted to the Firehawk configuration or the Firehawk can be built as a new model. The LA County Fire Dept has an air operations webpage with pictures of one of their three Firehawks and a description of the fixed tank system.

Type 1 Helos: Croman Helos

Last year I embedded some footage of a Croman Sikorsky S-61 here. That video has been removed by the user. For those of you who have found your here, enjoy this footage of Croman Helos shot in 2008.

Happy Thanksgiving everyone!

Type 1 helicopters: Sikorsky S-61

The Sikorsky S-61 is the civilian version of the SH-3 sea king. The first operator of the S-61 was Los Angeles Airways, using them for passenger service starting on March 1, 1962. Passenger capacity is up to 30 passengers depending on the variant (there are six variants).

Some nice pictures and a video of the S-61 may be found here

Specifications for the S-61 (Frawley, Gerard: The International Directiory of Civil Aircraft, 2003-2004, page 194. Aerospace Publications Pty Ltd, 2003 cited by http://en.wikipedia.org/wiki/Sikorsky_S-61)

Typical Specifications (exact specifications depend on the variant)
Crew: 2 pilots
Capacity: up to 30 passengers
Length: 58 ft 11 in (17.96 m)
Rotor diameter: 62 ft (18.9 m)
Height: 17 ft 6 in (5.32 m)
Disc area: 3,019 ft² (280.6 m²)
Empty weight: 12,336 lb (5,595 kg)
Loaded weight: lb (kg)
Maximum takeoff weight: 19,000 lb (8,620 kg)
Powerplant: 2× General Electric CT58-140 turboshafts, 1,500 shp (1,120 kW) each

Performance
Maximum speed:166 mph (267 km/h)
Cruise speed: 120 kn (222 km/h)
Range: 450 NM (833 km)
Service ceiling: 12,500 ft.
Rate of climb: 1,310-2,220 ft/min (400-670 m/min)

Croman Corporation has S-61's with 1,000 gallon fixed tanks used for firefighting operations. Croman has a page with pictures and videos of their firefighting S-61's.

Type 1 helicopter loading retardant from dip tank

I came across this video on you tube the other day. I a am pretty sure that this is a type 1 helicopter, possibly one of Columbia Helicopters tandem helicopters loading retardant from a dip tank. The helo was fighting fires in 2008 (I believe) in or near Tahoe National Forest in CA.

Type 1 Helicopters: fire fighting with Columbia Helos

To be honest, I am not quite sure which one of Columbia's tandem rotor helicopters is the star of the video, the Boeing Vertol 107 or the Boeing 234 Chinook. But you will get an idea of the fire fighting capabilities of Columbia's heavy lift, tandem rotor, helicopters. The video is shot from a camera on the pilot's helmet. In addition, you will hear audio feed of radio communications.

In addition, you might want to go and watch this video from Columbia. Here you will see more footage demonstrating the bucket operations.

Enjoy!

Type 1 Helicopters: Boeing Vertol 107

direct link to video

Columbia helicopters has a smaller tandem rotor helicopter, the Boeing Vertol 107. This is the civilian version of the CH-46 Sea Knight. Some pictures and a video of the CH-46 may be found here. Go to this location for the wikipedia entry for the CH-46 Sea Knight. I think that the tandem helicopter shown in the video that I embedded here is the Boeing Vertol 107.

Columbia purchased the type certificate to the Boeing Vertol 107 in December 2006. The 107 can carry a 1,100 gallon bucket. Spend a little time exploring the Columbia Helicopter webpage and you will find some photos of the Boeing Vertol and a video gallery featuring the Boeing Vertol 107 and its bigger brother, the Boeing 234 Chinook.

Specifications for the Boeing Vertol 107 may be found here.

Update on October 6, 2014:  The video that I originally embedded here of a Boeing Vertol 107 on wildland fire operations is no longer available. I found a video on the start up and departure of Vertol 107 that I thought you'd enjoy.

Ortega Fire: kudos to aerial firefighters.

I spent about an hour yesterday afternoon watching live streaming of the Ortega Fire burning in southern Riverside County, CA (south and east of Los Angeles. To see a map of this rugged area near the Cleveland National Forest, go here. The fire started late yesterday morning when a tractor knocked down an electric pole with a transformer, sparking the fire.

A couple of things that I want to point out. As I was watching the live streaming, I heard someone say (I assume the news helo reporter) that the winds were light or nonexistent. On the downside, they talked about high levels of fuels (vegetation) "fueling" the wildfire. Another downside, while there were a lot of ground crews fighting the fire, the steep terrain meant that the ground crews had a difficult time getting in and fighting the fire safely. This is the type of fire where aerial firefighting air craft can make all the difference.

Fortunately, there were aerial resources available and fighting the fire from above, two S-2's that I believe were from Hemet-Ryan, and four helicopters including one helitanker.

I have to say that I watched with awe as the fire grew during the time I was watching the live feed. I watched as embers blew down from the top of the ridge to an area down slope. The fire made a quick run up the mountain, impressive. I am told that I was watching something known as the chimney effect. And I watched the helos and the air tankers make drop after drop. See this news report from myfoxla for more information.

The good news is that what was reported as 10% containmentlate yesterday afternoon is now 75% containment. I understand that the latest estimate has firefighters containing this fire by around mid-day today.

Type 1 helicopters: Boeing 234 Chinook

A while back, I was visiting a friend who had spent some time in the military and was familiar with some of the helicopters then in use by the military, including the CH-47 Chinook helicopter. At some point the subject of my blog came up, he briefly mentioned the afore mentioned chinook helicopter, and suggested that I check out Columbia Helicopters.

I did so, and found that Columbia Helicopters uses the civilian version of the CH-43 Chinook, the Boeing 234 Chinook, for fire fighting operations. That was when I decided to spend a little time writing about the Boeing 234 Chinook and other type 1 or heavy firefighting helicopters. According to the Interagency Helicopter Operations Guide (chapter 6), a type 1 or heavy helicopters is defined as:

having at least 15 passenger seats or 5,000 lbs payload, 700 gallon retardant/water capacity, and maximum gross takeoff/landing weight of at least 12,501 lbs.

In the video you will see two of Columbia's heavy lift helicopters in action, the Boeing 234 Chinook and the Boeing 107 Vertol. I will be writing about the Boeing 107 Vertol in a later post. As you can see from the above video, both are tandem rotor helicopters.

The wikipedia entry on the CH-47 Chinook may be found here. More information, including some photos of the Boeing 234 Chinook may be found here.

Columbia has three variants of the Boeing 234 Chinook, the utility, combi, and the LR:

234 utility specifications
234 combi specifications
234 LR specifications

If you go the main page of the Columbia Helicopters web page (sorry that I can provide a direct link, and click on the operations menu and then on flight operations you will find their "fighting wildfires" page. You will see that the Boeing 234 Chinook carries a 3,000 gallon bucket, has a foam tank and is capable of carrying what Columbia calls long-term retardant.

I'd like to thank my friend and aviation historian, T, for his assistance in helping me find the links that I have included here and for the links in upcoming posts.

A quick note

In case any of you are wondering, I do not live anywhere near the flood affected areas. The storm system that has ravaged the southern areas of the Jersey shore and has also ravaged areas south of us is supposed to be pulling away from Jersey today. I understand from the weather channel that areas south of us, for example Norfolk VA were hard hit with flooding and rain fall in the double digits.

update on northeaster off northeast coast

The storm continues to slowly move up the mid atlantic and northeast coast. Myfox Philly has a map of wave heights as reported by buoys and ships. Impressive wave heights. I noted some buoys reporting 15 to 20 foot wave heights. Here is a slide show of some images of the flooding.

The Press of Atlantic City has a web page with reports of the storm and videos, it may be found here.

I understand that the NJ Forest Fire Service has been helping out with evacuations from Wildwood. See this thread on wildland fire for more information.

Coastal Flooding in southern New Jersey

I want to pause and write about the northeaster that is slowly moving its way up the eastern seaboard.

This storm -- the remnants of Tropical Storm Ida -- has been affecting southern NJ, Delaware and environs for a couple of days with rain, high winds (gusts ranging from 40 mph to 59 mph), and severe coastal flooding. For those of you who are interested, the latest advisories from NOAA may be found here. In the event that the link expires, I am copying the flood advisory below.

A fishing boat, the Sea Tractor was lost in rough seas from this storm off of Cape May, NJ on Wednesday night. The Coast Guard has suspended the search. For more information, see this article.

Coastal Flood Warning


COASTAL HAZARD MESSAGE
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
239 PM EST FRI NOV 13 2009

DEZ001>003-NJZ012-013-016-020>023-027-140500-
/O.CON.KPHI.CF.W.0004.000000T0000Z-091114T1500Z/
NEW CASTLE-KENT-INLAND SUSSEX-MIDDLESEX-WESTERN MONMOUTH-SALEM-
OCEAN-CUMBERLAND-ATLANTIC-CAPE MAY-SOUTHEASTERN BURLINGTON-
239 PM EST FRI NOV 13 2009


...COASTAL FLOOD WARNING REMAINS IN EFFECT UNTIL 10 AM EST
SATURDAY...


A COASTAL FLOOD WARNING REMAINS IN EFFECT UNTIL 10 AM EST
SATURDAY.


HIGH PRESSURE TO OUR NORTH AND LOW PRESSURE TO OUR SOUTH WILL
MAINTAIN A NORTHEAST TO NORTH WIND ALONG THE COASTS OF NEW JERSEY
AND DELAWARE INTO THE WEEKEND. THE FLOW WILL KEEP WATER FROM
DRAINING AWAY FROM THE COASTLINE AND TIDAL DEPARTURES WILL REMAIN
QUITE HIGH. WATER WILL BE TRAPPED IN THE BACK BAYS OF NEW JERSEY AND
DELAWARE FOR AT LEAST ANOTHER THREE OR FOUR TIDE CYCLES.


WHILE THE HIGH TIDE EARLY THIS MORNING WAS LIKELY THE HIGHEST OF
THE STORM... MODERATE TIDAL FLOODING IS EXPECTED AGAIN DURING THE
HIGH TIDE CYCLES LATE THIS AFTERNOON INTO THIS EVENING AND EARLY
ON SATURDAY MORNING. AS A RESULT... THE COASTAL FLOOD WARNING
CONTINUES INTO SATURDAY.


FOR SANDY HOOK... NEW JERSEY ON THE BAY SIDE... THIS AFTERNOON`S
HIGH TIDE IS AT 451 PM WITH A FORECAST HEIGHT AROUND 7.5 FEET
MLLW. THE HIGH TIDE EARLY ON SATURDAY MORNING OCCURS AT 526 AM
WITH A FORECAST HEIGHT AROUND 7.5 FEET MLLW.


FOR SEASIDE HEIGHTS... NEW JERSEY ON THE OCEANFRONT... THIS
AFTERNOON`S HIGH TIDE IS AT 421 PM WITH A FORECAST HEIGHT AROUND
7 FEET MLLW. THE HIGH TIDE EARLY ON SATURDAY MORNING OCCURS AT
456 AM WITH A FORECAST HEIGHT AROUND 7 FEET MLLW.


FOR ATLANTIC CITY... NEW JERSEY ON THE OCEANFRONT... THIS
AFTERNOON`S HIGH TIDE IS AT 437 PM WITH A FORECAST HEIGHT AROUND
7 FEET MLLW. THE HIGH TIDE EARLY ON SATURDAY MORNING OCCURS AT
509 AM WITH A FORECAST HEIGHT AROUND 7 FEET MLLW.


FOR CAPE MAY... NEW JERSEY ON THE OCEANFRONT... THIS AFTERNOON`S
HIGH TIDE IS AT 511 PM WITH A FORECAST HEIGHT AROUND 8 FEET MLLW.
THE HIGH TIDE EARLY ON SATURDAY MORNING OCCURS AT 543 AM WITH A
FORECAST HEIGHT AROUND 8 FEET MLLW. WATER LEVELS IN THE BACK BAYS
WILL LIKELY RUN FROM ONE HALF TO ONE FOOT HIGHER THAN THOSE ALONG
THE OCEANFRONT.


FOR LEWES... DELAWARE ON THE BAY SIDE... THIS AFTERNOON`S HIGH
TIDE IS AT 551 PM WITH A FORECAST HEIGHT OF 7 TO 7.5 FEET MLLW.
THE HIGH TIDE EARLY ON SATURDAY MORNING OCCURS AT 621 AM WITH A
FORECAST HEIGHT OF 7 TO 7.5 FEET MLLW.


FOR REHOBOTH BEACH... DELAWARE ON THE OCEANFRONT... THIS
AFTERNOON`S HIGH TIDE IS AT 450 PM WITH A FORECAST HEIGHT OF 7 TO
7.5 FEET MLLW. THE HIGH TIDE EARLY ON SATURDAY MORNING OCCURS AT
522 AM WITH A FORECAST HEIGHT OF 7 TO 7.5 FEET MLLW.


FOR REEDY POINT... DELAWARE... HIGH TIDE OCCURS AT 822 PM THIS
EVENING WITH A FORECAST HEIGHT AROUND 8 FT MLLW. THE HIGH TIDE ON
SATURDAY MORNING OCCURS AT 850 AM WITH A FORECAST HEIGHT OF 7.5 TO
8 FEET MLLW.


CONDITIONS ARE FORECAST TO IMPROVE GRADUALLY LATE IN THE WEEKEND.


PRECAUTIONARY/PREPAREDNESS ACTIONS...


A COASTAL FLOOD WARNING MEANS THAT FLOODING IS OCCURRING. COASTAL
RESIDENTS IN THE WARNED AREA SHOULD BE ALERT FOR RISING WATER AND
TAKE APPROPRIATE ACTION TO PROTECT LIFE AND PROPERTY.


DO NOT PARK YOUR VEHICLE IN A LOCATION THAT IS PRONE TO TIDAL
FLOODING. ALSO... AVOID ROADWAYS THAT ARE PRONE TO TIDAL
FLOODING.

Importance of safe aerial operations

I had hoped to be able to begin writing today about some of the other weather conditions and visibility limitations that can ground fire fighting aircraft. This would be a nice follow-up to my recent posts about winds. My idea was to begin by writing about fog, so I have spent some time over the three days or so reading more about fog and then look at other weather conditions and visibility limitations that can ground air tankers.

As sometimes happens, I found that I need more time before I am ready to write about fog, other visibility limitations that can ground air operations. I have written about winds grounding aerial fire fighting operations, and I suspect that there are other weather related conditions that can ground air operations. Thunderstorms come to mind, and perhaps there are more.

But while I do need more time before I can write about some of these issues in more detail, I do want to emphasize the importance of safety. Tankers and helicopters will not fly when conditions are present -- high winds, turbulence, fog, thunderstorms, other visibility restrictions, etc. -- that will jeopardize safe aerial firefighting operations.

While I am learning more about fog, inversions, thunderstorms and the like, I will continue to write about other topics. For example, I have promised some friends that I will write more about some of the different types of helicopters used in firefighting. I will begin doing so on Monday.

In the meantime, I want to leave you with this thought:

Lives are not replaceable.

Air Operations on Sheep Fire (Oct. 2009)

Aerial firefighting operations can be grounded reasons other than high winds and turbulence. One example is fog. Another example is thunderstorm activity. I had hoped to write something in a little more details about fog today. Unfortunately, that post will have to wait.

In the meantime, enjoy this video. It was shot by Nick Mitchell at the Sheep Fire that burned outside of Los Angeles in early October. According to Nick's blurb on youtube, the video was shot before air operations were grounded due to 50 mph winds on nearby ridges.

Lives are not replaceable

I have been giving considerable thought to one of the last sentences in my post of November 6.. Recall that I ended with:

Strong winds and bad turbulence are dangerous to all aviation interests, include aerial firefighting operations, leading to grounding of aerial fire fighting operations. So, if you are living near a wildfire AND the winds are strong AND you don’t see tankers and helicopters making retardant or water/foam drops on the fire there is a reason. They are not flying because it is not safe to do so.

I gave careful consideration to what I can add given that I am not an aerial firefighter. Nor am I resident of the wildland/urban interface in parts of America that are especially vulnerable to wildland fires such as southern California, the southwest, the northwest, etc. Nor am I a (ground) wildland fire fighter. For that matter, I am not a structure firefighter nor am I a first responder (e.g. EMT).

But I have been writing about aerial wildland firefighting for about ten or eleven months now, and I have learned a lot of things, including (and not limited to) reasons tankers don't fly. That is:

• Lives are not replaceable.
• Pilots and crews care about what they do, and they are good at it. They want to help the wildland firefighters on the ground protect your home, AND they want to do so safely.
• Lives are not replaceable.
• Strong winds, rotors and turbulence WILL overpower an airplane. Flying in strong winds and turbulence including but not limited to downdrafts and rotors puts pilots and crews at great risk for fatal crashes.
• Lives are not replaceable.
• Pilots want to be safe, they don't have a death wish. And they want you to be safe.
• Lives are not replaceable.
• Not only does a tanker crash put the lives of the pilot and crew in jeopardy, it puts the lives of all those on the ground in jeopardy as well. This includes you, your family, and your neighbors.
• Lives are not replaceable.
• Perhaps wildland firefighters on the ground can save your house, but they won't be able to save your house if a tanker crashes into it.
• Lives are not replaceable.
• Post-crash fires might exacerbate an already bad situation, perhaps increasing the size of the wild fire.
• Lives are not replaceable.

In summary, there are certain rules with regard to sustained and gusting winds and turbulence that tanker pilots must deal with.The most important one being, If the winds are blowing strong enough that aircraft are likely to be destroyed, they won't fly. But also, if winds are blowing strong enough that retardant will be blown away before it hits the ground, they don't fly.

Lives are not replaceable.



postscript: I read in one of the Interagency Online Aviation Training Modules that what is good for an airplane is also good for a helicopter. And what is bad for an airplane is bad for a helicopter. So, I assume (for the time being) that what I wrote above applies equally to airplanes and helicopters. I hope to look into how downdrafts, rotors, and turbulence affect helicopters flying fires in the coming weeks and will write about what I find here.

Why tankers don’t fly: safety concerns and high winds

If you have been following recent LA Times articles, see for example this article , or Bill Gabbert’s blog then you know valid concerns have been raised regarding tankers and helicopters not being deployed to the Station Fire in the early morning hours of the second day of the Station Fire. These are legitimate concerns that should be addressed, however I am not addressing them here. Rather, I am concerned with high winds as a reason why tankers and helicopters don’t fly.

Knowing that many fires out west are in or near mountainous terrain, I got interested in learning more about winds and turbulence that occur in mountains and how they affect aviation interests. I went first to one of my general aviation books -- The Complete Pilot by Bob Gardner. Here I read about what is known as mechanical turbulence. If I understand mechanical turbulence correctly, mechanical turbulence occurs when a building or a mountain disturbs that the flow of the wind current, sometimes creating strong downslope winds on the lee side of the building or mountain. These winds are also known as down drafts or bad air. Strong down drafts (see the picture above) can have more down power than airplanes have climb power. A pilot caught in such a down draft may not be able to fly out of the downdraft.

The picture below illustrates something known as rotor winds, a pilot unfortunate enough to tangle with these winds is flying into winds that are likely to overpower an aircraft with often fatal consequences.

There have been fatal tanker crashes while flying fires where down drafts and/or rotor winds may have been a major factor in the crash including a fatal crash out west in the late 1990s and one or two fatal crashes in the 1970s (also out west).

Wind and turbulent conditions can be forecast by meteorologists. Strong winds and bad turbulence including but not limited to rotors and down drafts are dangerous to all aviation interests, including aerial firefighting operations, leading to grounding of aerial fire fighting operations. So, if you are living near a wildfire AND the winds are strong AND you don’t see tankers and helicopters making retardant or water/foam drops on the fire there is a reason. They are not flying because it is not safe to do so.


REFERENCES

For more information about mountain wave turbulence, please go to this web page from the Australian Transport Safety Bureau, they are the source of the images that I have included here. I like that document, not only for the wonderful graphics but for a short and succinct explanation of mountain wave turbulence. While written for the Australian audience, I certainly got a lot out of it. Sparky Imeson, who wrote a book about mountain flying writes about mountain waves and rotor winds here. Sadly, Sparky died when his plane crashed earlier this year. His family is keeping up his web page on mountain flying. He has numerous articles on many other subjects related to mountain flying and I highly recommend them.  If I am correct, I believe he gave presentations on mountain flying at training sessions for air tanker pilots. I myself have spent at least a couple of hours on his website, and find myself frequently referring to it.