{"id":3490,"date":"2018-07-02T13:49:55","date_gmt":"2018-07-02T18:49:55","guid":{"rendered":"https:\/\/doctoraviation.com\/?p=3490"},"modified":"2018-07-02T14:02:19","modified_gmt":"2018-07-02T19:02:19","slug":"wind-shear-in-denver","status":"publish","type":"post","link":"https:\/\/doctoraviation.com\/wind-shear-in-denver\/","title":{"rendered":"Wind Shear in Denver"},"content":{"rendered":"

Wind shear in Denver.\u00a0 It was the first day of summer, June 21, 2018.\u00a0 I was enroute to Denver on Allegiant Flight 1320.\u00a0 Aside from an initial delay in loading the aircraft, due to having too many ticketed passengers, the flight had been uneventful.\u00a0 That all changed on final approach.<\/p>\n

<\/figure>\n

We approached Denver International Airport around 5:00pm MDT.\u00a0 It was fairly clear outside with some haze and clouds over the Front Range of the Rockies in the distance.\u00a0 As we descended on final approach, I looked out the window to the left.\u00a0 I saw another airliner in a steep climb.\u00a0 Moments later, I felt our nose rising and the power coming in abruptly on our own aircraft.\u00a0 Before most passengers knew it, we were in a steep climb.\u00a0 WIND SHEAR was my first thought.<\/p>\n

What is Wind Shear?<\/strong><\/p>\n

In all of my years of piloting, wind shear was one of the few phenomenon that I feared.\u00a0 The main reason for that fear is that the pilot has no control over wind shear.\u00a0 \u201cWind shear is a change in wind speed and\/or direction over a short distance,\u201d as defined by the FAA. Wind shear can take many forms, but the most concerning for pilots is when a headwind on final approach becomes no wind, or worse yet, a tailwind.\u00a0 The Federal Aviation Administration (FAA) had published an excellent white paper on the subject:\u00a0 https:\/\/www.faasafety.gov\/files\/gslac\/library\/documents\/2011\/Aug\/56407\/FAA%20P-8740-40%20WindShear%5Bhi-res%5D%20branded.pdf<\/a><\/p>\n

Wind shear is discussed in detail in Session 14 of Doctor Aviation (https:\/\/doctoraviation.com\/about\/<\/a>).\u00a0 However, for a quick primer, below is a picture of wind shear.\u00a0 In the diagram, the airliner is approaching the runway on the right side of the picture.\u00a0 Initially the aircraft is experiencing a headwind.\u00a0 Suppose the headwind is 20 knots.\u00a0 This will help the aircraft keep its desired approach speed of 150 knots.\u00a0 However, as the aircraft goes forward and descends, suddenly a 20 know tailwind can be experienced.\u00a0 Now the airspeed will suddenly drop from 150 knots to 110 knots, which can cause a stall and crash.\u00a0 See the equations below the diagram.<\/p>\n

<\/figure>\n

Equation 1: Approach Speed is 150 knots.\u00a0 130 knots (from the engines) + 20 knots (from the headwind)<\/p>\n

Equation 2: Approach Speed is now 110 knots.\u00a0 130 knots (from the engines) \u2013 20 knots (from the tailwind)<\/p>\n

Meanwhile, On the Flight<\/strong><\/p>\n

Back to my flight on June 21.\u00a0 As we climbed out and away from our initial approach, I could tell the lady next to me was very nervous.\u00a0 I shared with her that I was a retired Air Force pilot and that we had likely experienced wind shear.\u00a0 I gave her a very tame explanation of wind shear and told her that honestly, my confidence in the aircrew was increased due to their quick and proper reaction to the situation.<\/p>\n

<\/figure>\n

Denver, in particular, in susceptible to wind shear due to its location on a plain.\u00a0 The mountains rise, suddenly, and sharply to the west.<\/p>\n

The flight attendant announced that the captain had seen fit to discontinue the approach and that we would be going around for another approach.\u00a0 The captain would inform us of the situation, time permitting.\u00a0 He never came over the intercom.<\/p>\n

<\/figure>\n

After we landed the lady next to me shared that she didn\u2019t particularly like flying to begin with.\u00a0 So she thanked me for my explanation, which had helped to calm her.\u00a0 I waited until all the passengers had deplaned and then approached the pilot at the front of the cabin.<\/p>\n

I explained that I was a long time pilot.\u00a0 \u00a0\u201cSo did we get some wind shear on final,\u201d I asked.\u00a0 He looked surprised.<\/p>\n

He perked up and told me that the two planes in front of us had also gone around.\u00a0 I mentioned that plane I saw on approach to the parallel runway to our left was also going around.<\/p>\n

We talked about some of the warning signals the pilot now has.\u00a0 In this case, he received a verbal signal to pull up.\u00a0 Prior to about 20 years ago, the only indication of wind shear was a sudden drop (or rise) in airspeed.\u00a0 We have made strides in our aviation safety.<\/p>\n

I asked, how high the wind shear had occurred.\u00a0 He told me about 800 AGL (800 feet above ground level).\u00a0 I commended him for a job well done.<\/p>\n

I maybe experienced wind shear once or twice in my flying career and once before while flying commercial, I would be happy to never encounter it again, but it is a reality of flying.<\/p>\n

Ironically I flew with this same pilot on the way back from Denver the next Sunday.\u00a0 We experienced over half an hour of moderate turbulence at altitude on that flight.\u00a0 The most I had ever experienced.\u00a0 When I talked with the pilot after the second flight, he suggested maybe we should not fly together again due to our affinity for weird weather phenomenon.<\/p>\n","protected":false},"excerpt":{"rendered":"

Wind shear in Denver.\u00a0 It was the first day of summer, June 21, 2018.\u00a0 I was enroute to Denver on Allegiant Flight 1320.\u00a0 Aside from an initial delay in loading the aircraft, due to having too many ticketed passengers, the flight had been uneventful.\u00a0 That all changed on final approach. We approached Denver International Airport […]<\/p>\n","protected":false},"author":338,"featured_media":3499,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"footnotes":"","_jetpack_memberships_contains_paid_content":false,"jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false}}},"categories":[35],"tags":[484,819,820,818],"jetpack_publicize_connections":[],"acf":[],"yoast_head":"\nWind Shear in Denver - Doctor Aviation<\/title>\n<meta name=\"description\" content=\"I was enroute to Denver. 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