December 2009 - Posts
I came across this article today on armscontrolwonk.com, via two posts (here and here) on informationdissemination.net. The ArmsControlWonk article is a lengthy but an interesting read. I won't really get in the main point of discussion, "should the US Navy retired the nuclear-armed variant of the Tomahawk Land Attack Missile (TLAM-N)". That issue is well debated in the above links. The only thing I wanted to add to that discussion was if the situation is such that US has had to send nuclear tomahawks up to North Korea, then South Korea probably has a bigger problem to worry about than the occasional TLAM-N crashing (but not detonating I should point out) on its territory...
What I actually want to talk about was the guidance system of the TLAM weapon in general. I admit I don't know a whole lot about the Tomahawk, and much of what I learned was from this article, but what I did find out was quite surprising. Basically, the Tomahawk uses terrain mapping for guidance, using a radar altimeter to match surrounding terrain to a pre-programmed terrain map loaded onto the missile guidance software. From the article:
The problem is that the mid-1980s Tomahawk guidance system directs the missile to its target by comparing digital maps stored in an onboard computer against radar measurements of the terrain below the missile. The Nuclear Tomahawk, for example, needs to complete seven of nine “position-fixes” – matching a map to actual terrain — to arm the nuclear weapon. Each “fix” requires a map of rough and unique terrain approximately 7-8 kilometers in length. Since distinctive terrain is unusual by definition, the need for at least nine distinctive 8 km-long maps routinely results in routes of 100 km or more...
The probably wasn't a big deal against the Soviets, where there was lots of rough terrain to guide the missile along in Europe and Northern Asia. But in 1991's Desert Storm, the flat desert of Iraq did prove to be a problem. To fire the (conventionally armed) TLAMs from the Persian Gulf, the flight profile had to cross along the mountains of Iran to get enough fixes, before swinging west to Baghdad. Apparently this caused a stir at the White House, but was allowed to proceed. TLAM flights over Turkey and Syria (an alternative using Mediterranean-based ships) were prohibited.
Not until a few days before the war was to begin, however, had the White House and National Security Council suddenly realized that war plans called for dozens and perhaps hundreds of missiles to fly over Turkey, Syria, and Iran, the last a nation chronically hostile to the United States. President Bush’s advisers had been flabbergasted. (“Look,” Powell declared during one White House meeting, “I’ve been showing you the flight lines for weeks. We didn’t have them going over white paper!”) After contemplating the alternative-scrubbing the Tomahawks and attacking their well-guarded targets with piloted aircraft — Bush assented to the Iranian overflight. Tehran would not be told of the intrusion. But on Sunday night, January 13, Bush prohibited Tomahawk launches from the eastern Mediterranean; neither the Turks nor the Syrians had agreed to American overflights, and the president considered Turkey in particular too vital an ally to risk offending.
In the years following the 1991 war, conventional TLAMs were upgraded with GPS-assisted guidance systems, but apparently this didn't relieve them of this unique terrain overflight requirement, because the same situation presented itself during 2003's Operation Iraqi Freedom.
During the course of its flight along this “ingress route” a Tomahawk missile can drift off course and fly into the terrain that is supposed to guide it – an event known as “clobbering.” During the initial phase of Operation Iraqi Freedom in 2003, approximately ten conventionally-armed Tomahawk missiles went astray, crashing in Turkey, Saudi Arabia and Iran. In response to the political fallout from these stray missiles, the Navy suspended launches of Tomahawk missiles from ships in the Mediterranean and Red Seas. These Tomahawks were newer and had more modern guidance systems than the nuclear versions kept in storage since 1992.
Between 1.25% and 1.5% of TLAMs were lost due to "clobbering" during OIF according to the article.
What strikes me is that if the White House was "flabbergasted" by the missile routes in 1991, why was the problem not corrected? The US and co were basically in on-and-off conflict with Iraq for the entire time between the wars, so the idea that the newer upgraded TLAMs would be used against Iraq is obvious. And yet, the 2003 war rolls up and they are still sending Tomahawks on Baghdad-bound flights over Iranian territory. Since the '91 war, the TLAM has become a very popular weapon, with both ship and sub-launch capabilities, and some export success. They offer an effective, low-risk (no pilots to loose) solution to striking a well defended target. But this limitation to the guidance systems appears to be a significant weakness. Suppose in a future conflict, your enemy's neighbor, which you need to fly your missiles over, is on the edge of being hostile itself. Any weapons flying over in an indirect manner to its actual target could easily be perceived as an attack in progress against them, with many potential consequences. Never mind the idea of a state of the art missile simply crashing in the territory of an unfriendly country like Iran, giving up potential sensitive information on the TLAM system. (Also, does this mean the TLAM cannot be used for strikes against an island for example?)
It appears the political risks associated with the TLAM system have caused problems for the US in at least two wars now. Will this situation happen again? Hopefully not now. Since the 2003 Iraq War, the upgraded "Tactical Tomahawk" has been introduced into service. This has a much improved guidance system which could help avoid the political constraints of the past operational uses of the TLAM. It was a long time coming, but perhaps the solution is finally in place.
This article caught my eye, EADS builds case for A400M sale to USAF, coming not long after the type achieved it's first flight on Friday.
Apparently, the USAF will be wanting to buy the Airbus A400M to fill and airlift gap in the next five years, due to C-5A retirements, C-17 production shutdown, and C-130J performance limitations.
Maybe, but I'm not convinced.
Ok, let's assume that the USAF does start retiring C-5As early, and congress does allows the C-17 line to close soon. All that's left would be the C-130J (we'll leave the smaller C-27J out of this for now).
In this scenario, Airbus would certainly be in a strong position globally, offering the only strategic western airlifter, and for any other export country ordering perhaps a dozen aircraft, the A400M would be the only real option, and a good one. It breaks through the "20t bottleneck", offering a flexible blend of tactical transport and strategic airlift which would otherwise not be available to most air forces.
But the USAF is different. If we really are talking about a real "airlift gap", then the numbers will probably be quite substantial (at least 50?). The those kinds of quantities would certainly perk up interest from Boeing and Lockheed. Restarting the C-17 production line, perhaps with an updated model (like the proposed C-17B?) would be a plausible option. And Lockheed has been exploring the C-130XL concept which could bring the new Herc well above the 20t payload bracket, overcoming those "limitations" of the C-130J. True, development and/or retooling costs of either of these potential programs would have to be considered, and an order with smaller quantities would rule out some of the more ambitious redesign proposals to keep development costs in proportion. But given some of the political uproar we have seen over the KC-X, it is not at all improbably that Airbus would have to commit to building USAF A400Ms in the US itself. That will cost money too, plus any costs to changed or "Americanized" any of the aircraft's systems and capabilities. And don't forget the added operating costs to the USAF for having another totally unique aircraft in the fleet.
The A400M looks to be an excellent aircraft, and plugs a noticeable payload gap between the C-130J and C-17A. However, if this airlift gap does occur in the next 5 to 10 years (which in itself is a maybe), then Airbus won't be able to just waltz in like there's is the only available solution - it probably won't be. And if the latest KC-X RFP is anything to go by, in the end it will come down to cost, not necessarily capability (beyond the minimum requirements) - and who knows what unit costs will look like for a US A400M, let alone a C-130XL or C-17B.
The only situation where I would perceive the A400M as the only available option for the US military is if they needed a limited number of airframes to fulfill a particular special purpose requirement (and had to be bigger than the existing C-130J). Then yes, the Airbus plane is the only game in town. But for any big order, the A400M is likely going to have to face some competition.
The first real post!
Where to begin? There’s so much I could talk about from this past week, but one thing which got my attention in particular was United Airlines’ orders for both the Boeing 787 and the Airbus A350.
This one kind of caught me by surprise, mainly because I heard about the order on the radio driving to work that day, not my usual source of aviation news! At first I thought this was kind of an odd choice, splitting the order between the two manufacturers. No other US airline has done this (AA, CO, NW went for only 787s, US went for only A350s). However, when you look beyond the US, ordering both aircraft isn’t quite as uncommon as I first thought. Eight carriers (including some established names) have ordered both types - see the chart below. (Warning, I got my numbers from Wikipedia, and didn’t have a chance to verify them, so apologies in advance if there are any errors.)
Looking at the chart, I have a few observations, which again had not really struck me before:
--- The orders are always for different sized aircraft (i.e. no airline has ordered both the 787-9 and A350-800), which seems sensible enough obviously.
--- With the exception of Qatar Airways, the balance between the total A350 and total 787 orders has been virtually identical for each airline.
--- There is no real favourite in the most popular combination of 787 and A350 sizes, though the 787-8 and A350-900 combo (like United’s order) is more common. Only two of the airlines ordering any A350s also ordered the 787-9, with the majority ordering the -8, which has no A350 equivalent. (Did that make sense?)
--- Five of the carriers ordered capacity combinations that could not have been met by only the 787 family or the A350 family (i.e. ordered both the smaller 787-8 and the larger A350-900 or -1000). To me, this seems like the obvious reason to go for both types, but I wonder if this is a cause or effect of going for both types. I don't recall the specifics from the time, but I wonder what motivations were behind the other three carriers (Singapore, Etihad and Avianca) decisions to split their orders with no real advanatges from increased capacity options (not yet at least).
But maybe I'm just falling into the trap of using statistics to prove anything; after all, only a 1/3 of A350 customers have also ordered the 787, and only a 1/7 of 787 customers have also order the A350.
So let's just get back to the United order.
United have said that the plan is to reduce the current widebody fleet of three types (747, 767, 777) to these two new types only. So I guess that means United will be abandoning the high capacity market with no prospect of any A380s or 747-8s. That's another blow to the VLA programs, with one less potential customer to sell to, but I'm not really surprised. But in general, this move makes sense to me; United stated that this fleet renewal would reduce their long-haul seat count by 19%; this is a similar scale to their short-haul capacity reduction when they retired the 737s earlier this year. By getting smaller (on average) widebody aircraft, United can safely reduce capacity and cost without affecting flight frequency, which seems like a very smart move. And in the long-haul business, frequency can be particularly important, because one aircraft can affect your daily frequency by 50% or 100% between city pairs, which could easily influence overall passenger demand. Ultimately, United is reducing capacity but maintaining (even growing) it’s international network, which is what the passenger cares about most.
It also says that United is committed to focusing on capacity control and high load factors, and are sensibly taking actions to avoid the over capacity conditions of the US airlines of the late 90’s, which ultimately sent United and others into bankruptcy when the demand for travel collapsed.
Up until now, I thought United were kind of past it, a dinosaur of the old airline world. Even after their order announcement, I thought United's so cash strapped that they've split the order just to get better financing; and don't get me wrong, I'm sure the financial deals from Airbus and Boeing were very attractive. But after reconsidering this order a bit more, I really think that United is on the right track. They have a very clear vision going forward for their long-haul plans. The A350/787 fleet solution is simple and flexible, and their 50 options on each model leaves the door open for future 787-9s and A350-1000s, giving United even more flexibility for little added complexity. I wonder if many more airlines may take this split order approach going forward, as both development programs progress.
Hello and welcome to the trailing edge.
Until now I have been a frequent though passive visitor in the aerospace blog scene. Over the past couple of years I have read (and, as it turns out, been inspired by) the many excellent blogs and bloggers out there.
With views from the trailing edge, I hope to add me own (supplemental) take on what is going on in the world of aerospace and defense. I'm a generally mild-mannered person, and I hope to give a largely balanced opinion on what is going on in the industry, but I'll try to keep my posts interesting and insightful. I'm a US-based aerospace engineer by day, so don’t be surprised to see a few technical references and graphs pop up from time to time. Things will no doubt shift a little over time, but for now at least, expect this blog to focus primarily on the goings on of the airframers and engine makers in both the civil and defense aerospace markets, with maybe the occasional note from aviation history if anything catches my eye.
And I will of course welcome any and all comments, either posted on the blog itself, or by email.
So with introductions over, I’ll get on with my first real post.