{"id":25368,"date":"2024-06-05T07:34:38","date_gmt":"2024-06-05T11:34:38","guid":{"rendered":"https:\/\/ops.group\/blog\/?p=25368"},"modified":"2024-06-05T07:36:20","modified_gmt":"2024-06-05T11:36:20","slug":"se-asia-monsoon-season-what-are-lswds-and-why-will-they-cost-you-fuel","status":"publish","type":"post","link":"https:\/\/ops.group\/blog\/se-asia-monsoon-season-what-are-lswds-and-why-will-they-cost-you-fuel\/","title":{"rendered":"SE Asia Monsoon Season: What Are LSWDs and Why Will They Cost You Fuel?"},"content":{"rendered":"<p>June marks the start of <strong>monsoon season<\/strong> throughout Southeast Asia. From now until October, enroute weather deviations will routinely exceed 100nm.<\/p>\n<p>This creates a significant challenge for controllers and coordination between the high number of FIRs that span congested air corridors between <strong>Taiwan, Hong Kong, Singapore and Indonesia.<\/strong><\/p>\n<p>To make matters worse, the 2024 Monsoon season is predicted to be a bad one.<\/p>\n<p>And so, the answer is something called <strong>Large Scale Weather Deviation Procedures (LSWD)<\/strong> already innocuously appearing in FIR Notams like the one below.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone wp-image-25375 size-full\" src=\"https:\/\/ops.group\/blog\/wp-content\/uploads\/2024\/06\/Screen-Shot-2024-06-03-at-10.58.42-AM.png\" alt=\"\" width=\"604\" height=\"158\" srcset=\"https:\/\/ops.group\/blog\/wp-content\/uploads\/2024\/06\/Screen-Shot-2024-06-03-at-10.58.42-AM.png 604w, https:\/\/ops.group\/blog\/wp-content\/uploads\/2024\/06\/Screen-Shot-2024-06-03-at-10.58.42-AM-300x78.png 300w, https:\/\/ops.group\/blog\/wp-content\/uploads\/2024\/06\/Screen-Shot-2024-06-03-at-10.58.42-AM-600x158.png 600w\" sizes=\"auto, (max-width: 604px) 100vw, 604px\" \/><\/p>\n<p>This raises two important questions:<\/p>\n<ul>\n<li><strong>What does LSWD actually mean?<\/strong><\/li>\n<li><strong>What are operators doing about it?<\/strong><\/li>\n<\/ul>\n<p>In a nutshell, your standard contingency allowance may no longer be enough \u2013 meaning unfamiliar operators (especially on fuel critical routes) may unexpectedly be caught with their pants down.<\/p>\n<p>So, let\u2019s take a closer look.<\/p>\n<h4>The 2024 monsoon season is going to be bad.<\/h4>\n<p>The clever folk at the World Meteorological Organization recently said so.<\/p>\n<p>Last year, in comparison, was weak.<\/p>\n<p>You can take a look at their full report <a href=\"https:\/\/wmo.int\/media\/news\/above-normal-rainfall-forecast-southwest-monsoon-season#:~:text=Above%20normal%20rainfall%20is%20most,over%20much%20of%20the%20region.\" target=\"_blank\" rel=\"noopener\">here<\/a>, but the short story is that thanks to a spicy combination of \u2018ninas and ninos\u2019 much of Southeast Asia is about to receive up to ninety percent of its annual rainfall in the next few months. Which means <strong>large scale build-ups<\/strong> will be everywhere.<\/p>\n<h4>The airspace picture.<\/h4>\n<p>Spanning this area of unstable weather is a <strong>large number of adjacent FIRs<\/strong> serving some of the busiest air corridors in the world.<\/p>\n<p>Take this routing (WADD\/Bali to VHHH\/Hong Kong) as an example, overlaid with current precipitation in the region. It&#8217;s very early days, but you can already begin to see the extent of the deviations FIRs are dealing with.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-25376 aligncenter\" src=\"https:\/\/ops.group\/blog\/wp-content\/uploads\/2024\/06\/Screen-Shot-2024-06-04-at-6.25.48-PM.png\" alt=\"\" width=\"979\" height=\"640\" srcset=\"https:\/\/ops.group\/blog\/wp-content\/uploads\/2024\/06\/Screen-Shot-2024-06-04-at-6.25.48-PM.png 979w, https:\/\/ops.group\/blog\/wp-content\/uploads\/2024\/06\/Screen-Shot-2024-06-04-at-6.25.48-PM-300x196.png 300w, https:\/\/ops.group\/blog\/wp-content\/uploads\/2024\/06\/Screen-Shot-2024-06-04-at-6.25.48-PM-768x502.png 768w\" sizes=\"auto, (max-width: 979px) 100vw, 979px\" \/><\/p>\n<p>The sheer scale of weather deviations required by aircraft in this area creates a<strong> major challenge<\/strong> <strong>for air traffic control.<\/strong><\/p>\n<p>The lateral separation between adjacent airways is often far less than the deviation each aircraft will require, along with the narrower vertical margins of RVSM airspace.<\/p>\n<p>This creates numerous problems for controllers \u2013 providing priority handling to one aircraft creates delays and disruptions for others. <strong>It\u2019s your standard ripple effect.<\/strong><\/p>\n<p>To create room, ATC has specific protocols to manage these deviations. They call them LSWDs and they are used to reign in the mess.<\/p>\n<h4>How do these procedures work?<\/h4>\n<p>Traffic will be processed through a <strong>limited number of routes with level restrictions bound by their direction of flight.<\/strong> These routes can be found in each state\u2019s respective AIPs.<\/p>\n<p>Here&#8217;s an example found buried in Singapore&#8217;s docs:<\/p>\n<p><strong><img loading=\"lazy\" decoding=\"async\" class=\"size-full wp-image-25405 alignnone\" src=\"https:\/\/ops.group\/blog\/wp-content\/uploads\/2024\/06\/FLAS.png\" alt=\"\" width=\"805\" height=\"372\" srcset=\"https:\/\/ops.group\/blog\/wp-content\/uploads\/2024\/06\/FLAS.png 805w, https:\/\/ops.group\/blog\/wp-content\/uploads\/2024\/06\/FLAS-300x139.png 300w, https:\/\/ops.group\/blog\/wp-content\/uploads\/2024\/06\/FLAS-768x355.png 768w\" sizes=\"auto, (max-width: 805px) 100vw, 805px\" \/><\/strong>To make co-ordination easier between the numerous ATS sectors, <strong>all traffic operates with the same level availability whenever LSWDs are active.<\/strong><\/p>\n<p>For business jets, this may become problematic as <strong>higher flight levels (FL400+) may not be available<\/strong> for extended periods of time.<\/p>\n<p>As a locally-based G550 Captain explains:<\/p>\n<p><em>\u201cEven if higher flight levels are available in one FIR, controllers may be reluctant to give them to you. This is because there is no guarantee that the next sector can accommodate it and it can be hard to get you down again&#8230;<\/em><\/p>\n<p><em>\u00a0<\/em><em>&#8230;The main thing with LSWD is knowing that a lot of levels we usually get won\u2019t be available. And so, we carry more fuel accordingly. It may also be worth briefing the pax that conditions may be bumpier than they\u2019re used to&#8230;\u201d<\/em><\/p>\n<p>Flow control and crossing time restrictions are also common which may mean the use of <strong>less efficient mach numbers.<\/strong><\/p>\n<p>This can also lead to <strong>delays for start-up clearances<\/strong> due to enroute spacing. When asked what additional fuel our local G550 Captain carries for these procedures, his answer was this &#8211; &#8220;<em>at least thirty minutes.&#8221;<\/em><\/p>\n<h4>Have more to add?<\/h4>\n<p>Local operator feedback is invaluable to everyone in the group. If you\u2019ve got anything to add to this article, get in touch with us at <a href=\"mailto:team@ops.group\">team@ops.group<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>June marks the start of monsoon season throughout Southeast Asia. From now until October, enroute&#8230;<\/p>\n","protected":false},"author":49,"featured_media":25413,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[2256,774,227],"class_list":{"0":"post-25368","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-briefings","8":"tag-monsoon","9":"tag-southeast-asia","10":"tag-weather"},"_links":{"self":[{"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/posts\/25368","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/users\/49"}],"replies":[{"embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/comments?post=25368"}],"version-history":[{"count":14,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/posts\/25368\/revisions"}],"predecessor-version":[{"id":25411,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/posts\/25368\/revisions\/25411"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/media\/25413"}],"wp:attachment":[{"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/media?parent=25368"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/categories?post=25368"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ops.group\/blog\/wp-json\/wp\/v2\/tags?post=25368"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}