WHY is the Ronald Reagan Washington Airport A THING? (AA5342 Accident) - Page 1
Forum section: electronics / general

author: hans
author_rank: Super Contributor
timestamp: February 01, 2025, 01:46:23 am
content: The public transport route between the Dulles International Airport and Washington DC is around 45min, which is not great but also not terrible.I guess gov officials really want to have a nearby airport. Maybe this may not also be a convenience commute thing, but also a necessity for security and evacuation reasons (because why would they have a military base there as well..).However, having a national airport open to public with so much traffic in the middle of the city though.. I do agree its kind of nuts. Most airplane accidents happen during take-off/initial climb out and landing. And when engines give the ghost, you don't get to pick when to climb or try to make a turn. There are countless aviation disasters or near-misses which tells that story.But didn't a plane already crash into the Washington building on 9/11 as well?Not to say we don't have such things in EU. London also has the "London City" airport, which is a few km east of the city of London. It only has a single 1500m runway, and also a very non-standard 5.5 degree approach glidepath due to nearby buildings and whatnot. The standard ILS glidepath most airports use is 3 degrees. Normal medium-sized jets like the 737 or A320 cannot fly in. However, the Airbus A318 can (which is the 'very' short version of the popular A320), because they specifically added a steep approach mode to deal with it (presumably with adjusted warnings that would otherwise force pilots to abort the approach). And also presumably because the engines/wings are only slightly downsized compared to an A320, so it can also climb out safely on 1 engine. Kind of crazy to think I can hop on to Schiphol (NL) here and have 4 direct flights per day to this field.

author: Stray Electron
author_rank: Super Contributor
timestamp: February 01, 2025, 02:46:31 am
content: First, D.C. is filled withentitledpeople that don't like to waste any more of their time than they have to. Second, going out to Dulles takes at least an hour and a half each way and always involves heavy traffic. For many people that live in places like Arlington, they can take an Uber from the Reagan airport and be home in 15 to 20 minutes.DC didn't have nearly as much helicopter traffic until after 9/11 but now the GOV is expected to be able to fly out (like a bat out of hell!) anybody that is somebody in the event of an emergency (see Continuity of Government) as well as to provide daily helicopter flights for every politician that doesn't want to deal with DC traffic.Reagan airport is only supposed to handle 1500 flights per week but is currently handling about 2500 and the FAA justordered them(prior to the accident) to allow more flights despite objections of the airport management.To make matters worse; DC has an extremely limited subway system as compared to London. And that system is wearing out rapidly and is in dire need a complete overhaul.Because of COG and the Pentagon being in DC and other reasons, DC is literally very closely surrounded by military bases and airfields. So it's not just a matter of what the GOV requires but those bases all have their other jobs to do so it makes for a LOT of military helicopters and aircraft in very close proximity as well as two of the busiest commercial airports in the country.But didn't a plane already crash into the Washington building on 9/11 as well?One of the airplanes that was hijacked on 9/11 was flown into the Pentagon but that was a deliberate act and not an accident. But what you may be thinking of was when a B-24 crashed into the Empire State Building in New York City in about 1944.

author: coppercone2
author_rank: Super Contributor
timestamp: February 01, 2025, 02:59:36 am
content: they should just get back up politicians, i think they get enough perks as it isand they definitely don't need helicopters, basically they can fly when they start talking, just need a shopping bag and its basically mary poppins. politician holding a bag over their head practicing a speech = airborne

author: bdunham7
author_rank: Super Contributor
timestamp: February 01, 2025, 03:32:48 am
content: Have a look at Chicago Midway. The entire airport is 1 square mile in the middle of Chicagoland and it does similar passenger volume.Dulles is actually quite a trek so people go for DCA, including me. You can't fly direct to DCA from the west coast and there's no direct flight from our local airport to Dulles, so we'll take one connection (Midway) and be 20 minutes from wherever we're going. The convenience difference is huge. People have talked about a Hong-Kong style train from Dulles but there doesn't seem to be much will to do anything. Perhaps now that Shadow President Musk is there he can start boring that tunnel.The VFR helicopter routes are the real issue here IMO. For some reason they just abandon all typical aviation principles to allow helicopters to go whereever whenever. Same issues out here in SoCal but not quite as much confliction and I don't know of any VFR helicopter routes here that are limited to 200 feet. That seems pretty wild to me because helicopters are allowed "Special VFR" which means just enough visibility to get by--until it isn't, as in the Kobe Bryant crash.

author: pdenisowski
author_rank: Super Contributor
timestamp: February 01, 2025, 11:55:41 am
content: Quote from: hans on February 01, 2025, 01:46:23 amAs someone who used to fly to DC a lot for work: National is much, much more convenient when visiting .gov customers inside the Beltway. It's a lot easier to make a quick day trip to DC by plane if you fly into National. Dulles may have public transportation, but just getting through that airport takes forever, and in my experience check in and security are also more time-consuming at Dulles.Quote from: hans on February 01, 2025, 01:46:23 amThere are many airports in the United States where you're "gear down" over very densely populated areas. One could argue that National is a relatively safe approach, since (a) you don't (and typically can't) fly directly over "downtown" DC and (b) the approach is usually largely over water.But a terribly tragedy for everyone involved. Absolutely heartbreaking.

author: pdenisowski
author_rank: Super Contributor
timestamp: February 01, 2025, 11:59:51 am
content: Quote from: bdunham7 on February 01, 2025, 03:32:48 amThe one thing I still remember from my FAA exam prep was that the number one cause of accidents was VFR into IMC = CFIT**(Basically, planning to fly visually to your destination, getting into a weather situation where you can't see well and/or can't fly by instruments, and then flying into the ground)

author: TimFox
author_rank: Super Contributor
timestamp: February 01, 2025, 02:41:07 pm
content: Note that the local authority running the airports near Washington, DC kept trying to reduce the number of "slots" (flights in and out) at DCA due to safety concerns, but was always overruled by Congress (not the FAA) who wanted convenient non-stop flights to and from their constituencies.

author: Stray Electron
author_rank: Super Contributor
timestamp: February 01, 2025, 09:45:55 pm
content: I heard on the news this morning that the FAA has now shutdown all helicopter flights in the vicinity of Reagan airport for at least the next 30 days. I would have never believed that they would stop the COG practice flights!!! I don't know how far away from Reagan that the ban extends but it will certainly close Route 1, the route down the Potomac River that the helicopter was supposed to be following.Among other things that we're now learning is that the helicopter flights around DC are limited to 200 foot altitude (maximum) but the airliner was at 317 feet when it was struck and that the helicopter wasascending. Both D Trump and some of the news outlets have stated that the helicopter was also outside of it's assigned "lane" when it hit the airliner.And there is another mystery brewing. The US Army (who the helicopter belongs to) now says that the family of the helicopter pilot doesn't want her to be publicly identified! I'll refrain from expressing my opinion about that!

author: bdunham7
author_rank: Super Contributor
timestamp: February 01, 2025, 11:23:09 pm
content: Quote from: Stray Electron on February 01, 2025, 09:45:55 pmNot all routes are 200 feet--some are much higher--but the one they were on is indeed 200 feet north of the Wilson bridge. They also appear to have deviated to the west as well. However, an aircraft landing on 33 could be at or below 250 feet and still be on the glideslope. 50-100 feet vertical separation being "normal" is insane, IMO.https://aeronav.faa.gov/visual/09-05-2024/PDFs/Balt-Wash_Heli.pdf

author: CatalinaWOW
author_rank: Super Contributor
timestamp: February 02, 2025, 12:00:36 am
content: Just to pile on about the convenience of National (aka Ronald Reagan Airport). I also flew into the area regularly for various business reasons.Dulles is an expensive fare by cab, and no better served by rail/buses than anywhere else in the region. Dulles is also one of the less brilliant airport designs so landing, getting off the plane, collecting luggage and getting to transportation takes a relatively long time. And whatever mode of transportation you use, it is not particularly quick and often crowded and slow.All of that explains the pressure to keep it open. But the high traffic level is insane. Local politics also adds another pressure to this. In spite of wanting convenient airport access, the locals also want no airport noise, and so have compromised by limiting airport hours. Operating later at night and earlier in the morning could ease the pressure.

author: magic
author_rank: Super Contributor
timestamp: February 02, 2025, 12:20:40 pm
content: Quote from: Stray Electron on February 01, 2025, 09:45:55 pmReportedly it's been revealed that it was some chick on a training mission and they withheld her name because of Trump's rants about DEI. It will be interesting to find how she ended up outside the assigned path and right in the way of an approaching jet and how this fact apparently bothered nobody onboard the craft or at the ATC. Maybe business as usual over there...

author: EEVblog
author_rank: Unknown
timestamp: February 02, 2025, 12:33:35 pm
content: I've had countless people comment on this video as if they didn't even watch it.I proposed a quick high speed rail connection from Dulles direct to the center of DC. if implemted right it could literally be quicker than a cab ride to DC Reagan national.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 02, 2025, 01:18:35 pm
content: Dulles (indirectly) and Reagan (directly) are connected to the Metro subway system in DC.https://washington.org/navigating-dc-metrohttps://www.wmata.com/rider-guide/airport-and-rail/Everything without exception in DC is controlled by politics:1) Metro was costly to build, had cost overruns, delayed, and has problems. Still, many people use it, and there are many stops.2) Getting the political backing to eliminate or almost eliminate stops between Dulles and some terminal near the Capitol is unlikely.3) The cost might exceed the cost of buying Canada, Greenland, and Iceland.4) Dulles traffic has increased enormously since it was built. Even in the very late 80's one had little problem getting in and out in a small airplane (GA, non-trubine). Just fifteen years later, it was a different story. Reagan is also crowded, but convenient. Dulles might not be able to handle the additional, domestic traffic that DCA currently has.5) I have waited an hour for ground transportation from Dulles to nearby Chantilly, VA. So, it's not just distance to DC, it's also time to get out of Dulles.

author: nctnico
author_rank: Super Contributor
timestamp: February 02, 2025, 01:45:31 pm
content: Quote from: EEVblog on February 02, 2025, 12:33:35 pmThis is the US you are talking about. Public transport is a communist thing so they don't want it. Another problem with your solution is that the center of DC is not where the majority of people need to go. So there have to be many stops along the rail to get people where they get close to where they need to be. The biggest issue with public transport is that it takes you from a place you are not at to a place where you don't need to be.Also, judging by the comments from others, Dulles is like any large airport: slow and cumbersome. When I need to go to London, I use London City airport. Hell no to Heathrow as it takes forever to get through customs, immigration and security. So I totally get why people want to use the smaller airport.

author: coppercone2
author_rank: Super Contributor
timestamp: February 02, 2025, 02:20:25 pm
content: and now they are saying there is a altimeter discrepancy over 100 feet+-25feetso it could be a case of lowest bidder contract

author: pdenisowski
author_rank: Super Contributor
timestamp: February 02, 2025, 04:42:35 pm
content: Quote from: nctnico on February 02, 2025, 01:45:31 pmAmericanslovetaking public transportation in large cities in Europe / Asia: trains, subways, etc. Literally everyone who comes back from Europe / Asia talks about how much they like using public transportation. I don't think I'm exaggerating when I say that for most Americans, clean, safe, efficient public transportation is a tourist attraction in an and of itselfQuote from: nctnico on February 02, 2025, 01:45:31 pmThis is exactly correct. For the most part, opposition to public transportation in the United States is not ideological: it's entirely based on practical considerations.

author: bdunham7
author_rank: Super Contributor
timestamp: February 02, 2025, 05:09:19 pm
content: Quote from: EEVblog on February 02, 2025, 12:33:35 pmThe problem with magical rail connectors is that they rarely go close enough to your final destination to make it truly worth it. Even the excellent Hong Kong system usually requires a short cab ride at the end, although those are quite convenient and inexpensive so I'd rate that setup as good. I don't even want to go into the Heathrow train system. Just because something might make for a convenient commute doesn't mean it works for passengers with luggage.

author: jpanhalt
author_rank: Super Contributor
timestamp: February 02, 2025, 06:29:31 pm
content: Quote from: coppercone2 on February 02, 2025, 02:20:25 pmI find it hard to believe that a single, presumably barometric altimeter could be responsible. Aircraft of the complexity of the two involved would probably have multiple barometric and other altimeters. For civilian aircraft, barometric types must be certified every 2 years and accurate to ±20 feet at or below 1000 feet. I don't know the requirement for radio/radar altimeters. I suspect both aircraft had the latter type as well.Additionally, having gone through the violence, fire, and water of that crash, I would not be surprised if other mechanical instruments also were out of calibration.

author: NE666
author_rank: Frequent Contributor
timestamp: February 02, 2025, 07:48:11 pm
content: Quote from: jpanhalt on February 02, 2025, 06:29:31 pmAs far as I have read and understood it, the discrepancy being investigated is between the FL recorded by the FDR of the jet at the time of impact (325ft) and the FL of the helicopter at that time *as displayed to the tower controller* (200ft).Since the helicopter's FDR has yet to be processed, we don't know what its instruments were reading, only what the tower had. I have no idea whether the tower data comes from their own source (i.e. radar), or is what is being relayed to them by the helicopter's transponder.

author: bdunham7
author_rank: Super Contributor
timestamp: February 02, 2025, 09:02:16 pm
content: Quote from: NE666 on February 02, 2025, 07:48:11 pmThe airport radar doesn't provide altitude directly but relies on a transponder in the aircraft to send a return signal that includes altitude. I believe the type of transponder used in the Blackhawk would have resolution of 25 feet and an expanded uncertainty (k=2) of 125 feet. The instrument that the pilots see in the aircraft would be more precise and accurate. AFAIK both aircraft would have both a barometric and a radio (radar) altimeter in addition to any GPS-based spatial positioning system. The transponder data sent to the tower is not designed to be as precise and it would not be used to provide such small vertical separations.

author: EEVblog
author_rank: Unknown
timestamp: February 02, 2025, 09:38:19 pm
content: Quote from: nctnico on February 02, 2025, 01:45:31 pmThen you take the existing Metro system that's already in place.I'm talking about a direct dedicated high speed rail from Dulles to DC for those that need that route.QuoteSure, but if it gets overcrowded and dangerous as a result then something needs to be done.Will be interesting to see what happens with Sydney's 2nd airport in Western Sydney when it opens end of this year. It is 45km out from the city CBD and it'll take well over an hour on the metro to get to the city from there.

author: tooki
author_rank: Super Contributor
timestamp: February 03, 2025, 03:07:39 am
content: Quote from: hans on February 01, 2025, 01:46:23 amNote that the Metro connection to Dulles only happened in2022. Even with DC’s (by American standards) high transit usage, that’s still not very long to get people to change their habits, never mind for an entire industry to rearrange itself to route flights away from DCA.Not that Dulles could ever dream of absorbing DCA’s traffic. Dulles is already nightmarishly congested. (I once had a nearly 4 hour wait to get through security.) I avoid it at all cost when flying into the DC area (which is where I nearly always fly to when visiting USA, since that’s where all my friends are).Quote from: hans on February 01, 2025, 01:46:23 amLOL no, the politicians get evacuated by the military, not on commercial flights.DCA is critical to the region’s economy, as it is DC’s primary airport for short-haul domestic flights, together with BWI closer to Baltimore. Dulles is the big international airport, with nearly all the long-haul international flights from the area, as well as most of the long-haul domestic flights.(BWI is my preferred airport: aside from being a bit closer to the houses of the friends I stay with, it’s simply the most pleasant, friction-free airport of the three. It’s not a matter of cost, either: for fare purposes, IAD, DCA, and BWI are a single market, so essentially considered the “same” destination for ticket pricing.)Quote from: jpanhalt on February 02, 2025, 01:18:35 pmHuh? The silver line is a direct connection to Dulles.Quote from: EEVblog on February 02, 2025, 12:33:35 pmI haven’t yet watched the video. But I can say this: if you had been aware of how much effort and compromise and back-and-forth it took to get the Metro extended out there, you’d realize that a high-speed rail connection is… unrealistic for the foreseeable future.And this despite DC being one of the most heavily used transit systems in the country!With that said, even without it being high-speed rail, the Metro connection to Dulles is already much faster than taking a car.The big difficulty with the DC transit system — something people who aren’t from the area usually aren’t aware of — is that because the system operates in numerous jurisdictions, getting anything done requires agreement from all of them.The jurisdictions include two states (VA and MD), Congress (because DC is directly subordinate to Congress), five counties (three in VA and two in MD), plus the city governments of three VA cities (because all VA cities are independent cities, meaning they are not part of the surrounding counties but instead are equivalent to counties), plus the “independent” DC city government. Outsiders often think the DC city government somehow runs the show, but it is arguably the weakest of them all. Of all of these, the only entity with truly outsize power is Congress, which can unilaterally override the DC city government, and usually beats the state and county governments into submission, too, even though it doesn’t have quite as much legal authority over them.In fact, until the Metro system came to a crashing halt some years ago, midweek, with no notice, due to tunnel wiring issues so bad that inspectioncould not be delayed until the weekend— the result of 40 years of insufficient preventive maintenance due to the funding oddities — the Metro system did not even have a fixed baseline funding, but instead had to grovel to the two states and DCevery single year. This has luckily changed now, so long term planning is now more doable, and they’ve been working for years on catching up on the maintenance debt they had allowed to accrue.Quote from: pdenisowski on February 02, 2025, 04:42:35 pmExactly! In places like SF, NYC and DC, where transit is fairly robust by American standards, it is heavily used. (DC is second only to NYC for highest percentage of transit users in USA.)In DC, 35% of households do not own a car. By American standards that’shuge. Several hundreds of thousands of people commute to DC by metro every day. (IIRC typical daily ridership is 400K.) Locals try to use Metro into DC whenever possible, since parking in DC is difficult and/or expensive, but above all because DC road traffic is absolutely nightmarish at rush hour. (When I visited LA for the first time and experienced their rush hour traffic, I quipped “thislittle bit of traffic is what everyone makes such a fuss about?!?” Turns out that statistically, my impression was correct, too.)DC traffic is so bad, and has been for so long, that there is a local, semi-formalized form of carpooling with strangers called “slugging” that evolved in DC (later spread to a few other places). And that’swiththe hundreds of thousands of people off the roads thanks to the metro!

author: coppercone2
author_rank: Super Contributor
timestamp: February 03, 2025, 03:14:35 am
content: Quote from: bdunham7 on February 02, 2025, 09:02:16 pmare you sure they dont use the data the pilot sees and send it to the tower? Why would you do it any other way? That way the tower knows what the pilot sees. Not only could that help with planning, it also could be used for accident investigationIf its some isolated monitor, I don't know why their considering it in the investigation, seems dubiousAnd one article clearly says that it was the radar of the tracking station measuring the helicopter. So who the hell knows what their doing. The media reports are so contradictory and confusing it almost seems useless to try to study it right now, I feel like I am wasting my time

author: bdunham7
author_rank: Super Contributor
timestamp: February 03, 2025, 03:50:54 am
content: Quote from: coppercone2 on February 03, 2025, 03:14:35 amThere is no general statement you could make that would cover all the systems currently in use. Some will use data derived from the same systems that display to the pilot, others are more or less standalone devices. However the altitude information that they return is the "pressure altitude" based on an assumed barometric pressure at MSL of 29.92". This can vary quite a bit from the corrected altitude that the pilot sees.QuoteOne reason is that we're not talking about a clean sheet design with all the latest technology and ideas baked in. The tower doesn't need to know "what the pilot sees" when it comes to altitude, they need to see a reliable number that is consistent with the numbers from other aircraft. A transponder that just transmits an altitude number based on the barometric pressure as measured without correcting it for local conditions. It might not be very accurate but will be consistent with other transponders doing the same thing. This allows them to provide vertical separation and the accuracy is more than good enough to accomplish that. The radar display will typically adjust for local conditions and display a number that is closer to the real thing, but in reality the relative differences are all that really matter.QuoteYou expect the media to get it right?Some radars systems can return a vertical angle as well as the horizontal azimuth, but I don't think they're typically found in airports unless things have changed a lot recently.

author: coppercone2
author_rank: Super Contributor
timestamp: February 03, 2025, 04:29:56 am
content: Well then the tower should know if they were gonna crash or not crash?I think they just said that its around. not that your going to crash on that heading, if they had correct relative data, they should have been able to tell.Perhaps if the tower can't be a 2nd safeguard because its not accurate enough, then those flight paths should be banned for having a lack of redundancy. It makes it seem like their trying really hard to squeeze in edge cases.Would the tower not be yelling at the helicopter to drop or turn or something like 10 seconds before a impact? It says those helicopters turn really fast. I am not sure but I think a few seconds could have been enough, the RF stuff happens at nearly light speed and human response is around 250ms for experts

author: CatalinaWOW
author_rank: Super Contributor
timestamp: February 03, 2025, 04:36:39 am
content: Why military bases in the DC area? Mostly it is history. (I know, from a European view we don't really have history.)But bases there were often established long before airports, and largely expanded/built to support the US Civil War. Many of the major battles of that war were fought within 100 km of DC.And then things grew around that. And it really wasn't until well after WWII that there was much non=military and non-government activity in the area, so why not? You wouldn't want to use up valuable commercial real estate around Boston or New York or Philadelphia or .... And there really still isn't. The Federal bureaucracy constitutes most of the economic activity in the area.

author: bdunham7
author_rank: Super Contributor
timestamp: February 03, 2025, 04:41:09 am
content: Quote from: coppercone2 on February 03, 2025, 04:29:56 amThe system did display a CA warning but the helicopter crew requested "visual separation" meaning they said that they saw the other traffic and would avoid it. The system does not have nor should it have the level of precision to tell the controller that the aircraft will crash, just that they might. In most other situations this means keeping the aircraft much further apart. I've never heard of a system like this that permits the possibility of <100 feet of separation in normal operations.Edit: Looking further at the video it appears that there actually is no discrepancy at all so IDK what everyone is nattering about on every media outlet. The display showed 200 feet a few times before the crash but at the time of the collision both were reading out 300 feet on the ATC screen. The data from the planes FDR apparently indicates 325 feet. Where's the mystery?Is every talking head on your TV now a complete s**t-for-brains parrot? Wait, don't answer that...https://www.reddit.com/r/aircrashinvestigation/comments/1idnsy6/aa5342_playback_from_official_atc_radar_sources/

author: coppercone2
author_rank: Super Contributor
timestamp: February 03, 2025, 05:32:51 am
content: and I don't know if it truncates or rounds, people are saying no it trunkates no it roundssource code invesitgation requiredTrunkating is useful if you need to kill bullshit data (i.e. getting 6 digits on 12 bits) on the final displayand I don't see why the radar tower can't get better radars. it seems just like a money or technology thing.

author: bdunham7
author_rank: Super Contributor
timestamp: February 03, 2025, 05:44:05 am
content: Quote from: coppercone2 on February 03, 2025, 05:32:51 amWhy does that matter if both are the same?QuoteWhy? How would "better" (define that please) radar help?

author: coppercone2
author_rank: Super Contributor
timestamp: February 03, 2025, 05:49:03 am
content: because the tower would be bitching you out for at least 30 seconds to move if they were really sureAnd their not the same, wtf. 299 rounded is 3, trunkated its 2the utility of the tower is greatly increased if they have more resolution accuracy and faster feedback to help guide things in. if it was really good all your front panel instruments could go broke and you can fly it by audio instructions from the radio while riding a magic carpet, or even a packet modem to give you remote telemetry in nearly real time. like a cell phone app

author: bdunham7
author_rank: Super Contributor
timestamp: February 03, 2025, 06:04:00 am
content: The aircraft are each not on a steady course, the altitude and position didn't match perfectly until it was too late. There was no 30 seconds.And what I mean was that if both displayed numbers are the same, why does truncation vs rounding matter? If you have data accurate to 1 foot but then is truncated, then that "003" represents 300-399 feet. If it is rounded it represents 250-349 feet. If both aircraft are displaying "003" then they're in the same 100-foot band and what does it matter exactly which band it is? However, the data doesn't have 1-foot resolution at all as transmitted, it is a binary code that only has 9 or 10 bits and the LSD increment is 100 feet. Thus any rounding or truncating starts within the aircraft and then the ATC system has to perform a correction on that. IDK whether the altitude encoders can be said to "round or truncate" (I think the concept may not quite make sense in this context) but the end result is the same--the data is useful for comparing but only has 100 foot resolution.