Skip to main content

Mountain Flying Part 2

 

Continued from: Mountain Flying Part 1

Orographic Lifting

As the wind blows moist air upslope, it will cool, and may form clouds. If, as is often the case in winter, the air is stable, the clouds will stay close to the mountain, forming a cap cloud. However, if the air is unstable, as is usually the case in summer, this initial lifting will be enough to start convection and result in thunderstorm formation.

Microbursts

Wet microbursts are typically found in the middle of an active thunderstorm or intense rain shower, and avoiding the strong downdraft is relatively easy. Dry microbursts, however, are more insidious because they occur with little or no warning in the clear air beneath virga. Dry microbursts are common in and near the Rockies and other mountainous areas of the western United States in the summer. Dry microbursts are likely when thunderstorms with bases above about 3,000- to 5,000-feet above ground level (AGL ) exist and the temperature/dew point spread on the surface is more than about 40 degrees Fahrenheit. A good indicator of a dry microburst is when you see dust blowing underneath the thunderstorm. Staying clear until the event passes (usually a few minutes) is recommended.

Density Altitude

Density altitude is pressure altitude corrected for temperature. Higher density altitude reduces overall performance of the airplane. At higher density altitudes, takeoff and landing distances are increased, thrust is decreased, rate of climb and actual service ceiling are decreased, true airspeed (TAS) is higher for a given indicated airspeed (IAS), and turning radius is larger for a given IAS (due to higher TAS). To help regain performance at high-density altitudes, consider reducing aircraft weight (retardant and/or fuel load). Check your aircraft flight manual (AFM) performance data charts for takeoff and landing distances, climb rates, etc. Since your TAS is higher for a given IAS, many pilots respond to the visual cues of higher ground speed on takeoff by rotating at a lower IAS than normal. Rotating at too slow an airspeed may cause the airplane to take an even longer ground run than necessary. Turning radius is proportional to the square of TAS. For example, if you increase your TAS by only 10%, your turn radius will increase by 20%. In the fire pattern this may result in an overshooting turn to final with the resultant last-minute corrections (rushed approach, etc.). If in doubt, go around. Higher density altitudes also affect best rate and angle of climb airspeeds. Refer to your AFM to be sure you are flying the correct airspeeds to get the performance you expect. Be extra cautious about slowing down at high-density altitudes. Throttle response will be delayed (due to less dense air) and thrust is reduced due to less air over the prop blades. Stalls at high-density altitudes and close to the ground can be devastating with insufficient time or performance response to recover.

Ridge and Pass Crossing

A good technique is to cross ridges or passes at the ridge elevation plus at least 1,000-feet AGL. If the winds at mountain top level are above 20 knots, increase to 2,000-feet AGL. Plan to be at that altitude at least three miles before reaching the ridge and stay at that altitude until at least three miles past it. This clearance zone will give you a reasonable safety zone to avoid the most severe turbulence and downdrafts in windy conditions and/or the ability to turn the aircraft around in a descending turn if necessary. If conditions or airplane performance dictate, you may need to fly along the windward side of a ridge to find updrafts for gaining altitude before crossing a ridge. You may also need to circle before reaching the ridge if climbing out of a valley airport. Move across ridges at a 45° angle. This allows you to turn away from the ridge quicker if you encounter a severe downdraft or turbulence. Once you have crossed the ridge, turn away from it at a 90° angle to get away from the most likely area of turbulence quickly. Plan your crossing to give yourself the ability to turn and descend toward lower terrain quickly if necessary.

Rough Terrain

Heads up near or above abrupt changes of terrain such as cliffs or rugged areas. Dangerous turbulence can be expected, especially with high winds.

Box Canyons

Try to avoid flying up the middle of a canyon. It is better to fly along one side or the other (preferably the downwind side) at sufficient altitude to be in a better position to execute a 180-degree turn. Allowing sufficient altitude for a descending 180-degree turn along with a turn into the wind (if possible) decreases actual turn radius across the ground. Use extra caution when mountain tops are obscured. Many accidents occur as a result of pilots turning up the wrong drainage, ending in a box canyon. Monitor GPS closely.

 

 

Category

6MFS Suggestion Form


Have an idea or feedback?

Share it with the NWCG 6MFS Subcommittee
 


Follow NWCG on X and Facebook
 


 

Last Modified / Reviewed:

NWCG Latest Announcements

NEW! S-290, Intermediate Wildland Fire Behavior (Blended) Available Now

Date: Aug 15, 2025
Questions? Please contact:
Fire Behavior Subcommittee

NWCG is excited to announce that the S-290, Intermediate Wildland Fire Behavior (Blended) training is now available on the Wildland Fire Learning Portal. S-290 (Blended) training combines online training and instructor-led training components that support individuals working towards any Single Resource Boss or Fire Effects Monitor incident qualifications.

This second course in the series collectively serves to develop fire behavior prediction knowledge and skills, and provides more detailed information on fuels, weather, and topography that affect wildland fire behavior for safety purposes.

Students are required to finish the prerequisite S-190, Introduction to Wildland Fire Behavior, before enrolling in S-290, Intermediate Wildland Fire Behavior (Blended).

References:

S-290, Intermediate Wildland Fire Behavior (Blended)

S-190, Introduction to Wildland Fire Behavior

Wildland Fire Learning Portal

NEW! S-271, Helicopter Crewmember (Blended) Now Available

Date: Aug 14, 2025
Questions? Please contact:
Interagency Helicopter Operations Subcommittee

The S-271, Helicopter Crewmember (Blended) is now available. Developed through the Incident Performance and Training Modernization (IPTM) effort, this training supports individuals working towards Helicopter Crewmember (HECM) incident qualifications. 

S-271, Helicopter Crewmember (Blended) training combines online training and instructor-led training components. This course is designed to provide students with the knowledge and skills necessary to perform the duties of the HECM position, as described in the NWCG Incident Position Standards for Helicopter Crewmember, PMS 350-22.

Any changes to qualification pathways will take effect with the next update of the NWCG Standards for Wildland Fire Position Qualifications, PMS 310-1, scheduled for January 2026.

References:

S-271, Helicopter Crewmember (Blended)

NWCG Helicopter Crewmember (HECM) Position Page

Wildland Fire Learning Portal

Incident Position Standards and Next Generation Position Task Books Now Available for FBAN and LTAN

Date: Aug 13, 2025
Questions? Please contact:
Fire Behavior Subcommittee

NWCG is excited to announce that Incident Position Standards and Next Generation Position Task Books are now available for Fire Behavior Analyst (FBAN) and Long Term Fire Analyst (LTAN).

The Performance Support Packages for these positions were developed as part of the Incident Performance and Training Modernization (IPTM) effort. These resources support trainees, qualified personnel, and evaluators in their respective roles.

Any changes to qualification pathways will take effect with the next update of the NWCG Standards for Wildland Fire Position Qualifications, PMS 310-1, scheduled for January 2026.

References:

NWCG Fire Behavior Analyst Position Page

NWCG Long Term Fire Analyst Page

ETC/RMC Safety Bulletin: 25-001 New Guidance on Laundering Wildland Fire Clothing to Reduce Contamination

Date: Aug 8, 2025
Questions? Please contact:
Equipment Technology Committee
 Risk Management Committee

The Equipment Technology Committee (ETC) and the Risk Management Committee (RMC) have issued Safety Bulletin 25-001: Laundering to Decontaminate Wildland Fire Clothing. Recent research revealed that wildland fire flame-resistant pants and shirts can be contaminated with chemicals from combustion byproducts, including carcinogens, and that common laundering practices can effectively remove these harmful contaminants from wildland firefighter clothing more effectively than previously understood. It is recommended to decontaminate wildland fire clothing as frequently as possible. 

Frequently Asked Questions about this new information and how to implement recommendations can be found on the NWCG Alerts page. Read the complete ETC/RMC Safety Bulletin: 25-001 to learn more. 

References:

NWCG Alerts

ETC Safety Bulletin: 25-001

Frequently Asked Questions (FAQ) on Laundering to Decontaminate Wildland Fire Clothing

Equipment Technology Committee

Risk Management Committee